Photocatalyst Panel and Method for Continuous Hydrogen Production

Abstract

The present disclosure relates to a system and method for continuous hydrogen generation using a photocatalyst. Specifically, the present disclosure relates to a system and method for continuous hydrogen generation using a photocatalyst for water that utilizes semiconductor charge carriers immobilized on a removable carrier in the presence of a reducing agent such as a tertiary amine.

Description

Technical Field

[0001] The present disclosure relates to a system and method for continuously producing a predetermined product with a photocatalyst. Specifically, the present disclosure relates to a system and method for producing photocatalytic green hydrogen from water using a shaped nanoscale semiconductor incorporated into a panel by immobilization on a specific substrate in a closed redox cycle.

Background Art

[0002] Photocatalytic panels using sunlight can decompose water into hydrogen and oxygen and can be used to reduce CO2. However, there are several drawbacks to consider. For example, the efficiency of the panel may be poor, while the photocatalytic particles in the panel may also deteriorate over time, which may reduce the efficiency of the photocatalytic particles (and the panel). Furthermore, regular maintenance of the panel may be required to keep them functioning properly. Similarly, since the panel depends on sunlight to operate, it may not be very efficient in decomposing water or purifying wastewater flow on cloudy or rainy days.

[0003] Currently, green hydrogen is a major energy carrier candidate for applications that require a high energy density or for applications remote from the power supply grid and can function as a feedstock for chemical reactions to produce various synthetic fuels. Important rules are maintained when ensuring the future decarbonization of the energy system and the transition to a sustainable future. Although there are industrial methods for producing green hydrogen, these methods are not economically / cost-competitive with fossil-based polluting "gray" H2.

[0004] One possible technique for generating green hydrogen uses artificial photosynthesis (photocatalysis) for hydrogen generation from water by sunlight in a closed redox cycle. In such a photocatalytic process, photoinduced electron-hole pairs generated within semiconductor particles are utilized to facilitate desired chemical reactions with various substances. The nanostructuring and shaping of the photocatalytic particle system have been found to significantly improve the overall system efficiency.

[0005] Considering that photocatalytic semiconductor nanoparticles with sufficient efficiency and stability for solar green hydrogen generation have only recently come to light, systems and methods for incorporating them into panels enabling continuous operation have not yet been developed.

[0006] A stable semiconductor system with sufficient (albeit narrow) bandgap absorption in the visible range (e.g., 2.4 > X > 2.0 eV), as well as an electron affinity to drive visible light absorption and subsequent redox reactions, is challenging. Further issues faced by the photocatalytic process are the inevitable recombination of photoinduced charge carriers, particle disintegration, reverse reactions of intermediates on the catalyst surface, and reverse reactions of the products, in other words, unwanted termination reactions.

[0007] The disclosed systems and methods are intended to address these deficiencies. SUMMARY OF THE INVENTION

[0008] In various exemplary implementations, systems and methods for a water photocatalyst are disclosed that use shaped semiconductors (or photoinduced charge carriers) immobilized on an optionally removable transparent film under a closed redox cycle.

[0009] The exemplary implementations provided herein are systems for continuously generating hydrogen and include at least a partially transparent container having a first inlet and a second inlet and a first outlet and a second outlet, a pressurized water source in continuous liquid communication with the first inlet, a pressurized source of an electron donor compound, and at least one removable transparent film including a plurality of at least partially embedded shaped nanoscale semiconductors, each having a proximal end and a distal end, with a seed embedded in the shaped nanoscale semiconductor at the proximal end and a metal tip disposed at the distal end of the shaped nanoscale semiconductor.

[0010] In yet another exemplary implementation, a method for continuously generating hydrogen is provided herein. The method is implemented in a system including a transparent container having a first inlet and a second inlet and a first outlet and a second outlet, a pressurized water source in liquid communication with the first inlet, a pressurized source of benzylamine (BnNH2) in liquid communication with the second inlet, and at least one removable transparent film including a plurality of at least partially embedded shaped nanoscale semiconductors, each having a proximal end and a distal end, with a seed embedded in the shaped nanoscale semiconductor at the proximal end and a metal tip disposed at the distal end of the shaped nanoscale semiconductor. The method includes filling the transparent container with water using the first inlet, exposing the transparent container to actinic radiation of a predetermined wavelength, photocatalyzing the water using the plurality of shaped nanoscale semiconductors to form hydrogen, oxygen, and depleted water, contacting the container with the accumulated benzaldehyde in the presence of a nitrogen source using the second inlet, collecting the hydrogen using the first outlet, and removing the depleted water using the second outlet.

[0011] In yet another exemplary implementation, a method for continuously generating benzylamine implemented in a system is provided herein. The system includes a transparent container having a first inlet and a second inlet, and a first outlet and a second outlet, a pressurized water source in liquid communication with the first inlet, a pressurized source of benzylamine (BnNH2) in liquid communication with the second inlet, and at least one removable transparent film including a plurality of at least partially embedded shaped nanoscale semiconductors, each having a proximal end and a distal end, with seeds embedded within each of the shaped nanoscale semiconductors at the proximal end and metal tips disposed at the distal end of each of the shaped nanoscale semiconductors. The method includes filling the transparent container with water using the first inlet, exposing the transparent container to actinic radiation of a predetermined wavelength, photocatalyzing the water using the plurality of shaped nanoscale semiconductors to form hydrogen, oxygen, and depleted water, contacting the container with benzylamine in the presence of a nitrogen source (e.g., NH3 at a predetermined molar concentration) using the second inlet, collecting hydrogen using the first outlet, removing depleted water using the second outlet, and separating the accumulated benzaldehyde from the depleted water (e.g., by evaporation).

[0012] These and other features of the system and method for water photocatalysis using nanoscale shaped semiconductors immobilized on a removable membrane will become apparent from the following detailed description when read in conjunction with the drawings and examples, which are illustrative and not limiting.

Brief Description of the Drawings

[0013] For a better understanding of the system and method for using a water photocatalyst using semiconductor rods immobilized on a removable membrane in the presence of a reducing agent, reference is made to the accompanying examples and drawings with respect to its exemplary implementation.

[0014]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0015] Provided herein are exemplary implementations of systems and methods for continuous hydrogen production by photocatalysis of water, which utilize semiconductor charge carriers immobilized on a removable transparent film and water, optionally in the presence of a reducing agent.

[0016] Unlike bulk photocatalysts realized as thin films on conductive substrates, water splitting by nanoscale photocatalysts utilizes a photocatalytic material simply immersed in water. The principle of photocatalytic water splitting requires a high surface area for electron excitation and collection, as well as the use of oriented nanocatalysts that provide a high surface - area - to - volume ratio (A / V) and high light - collection efficiency. The disclosed semiconductor nanostructures improve photocatalysis through the combined effect of quantum confinement and unique surface morphologies.

[0017] Accordingly, in the exemplary implementations disclosed in FIGS. 1 - 2, what is provided herein is a system 10 for continuously generating hydrogen, a transparent container 100 having a first inlet 101 and a second inlet 102, and a first outlet 103 and a second outlet 104, a pressurized water source 111 in continuous (i.e., in a continuous flow) liquid communication with the first inlet 101, a pressurized source 112 of benzylamine in liquid communication with the second inlet 102, and at least one i-th removable transparent membrane 105i including a plurality of at least partially embedded shaped nanoscale semiconductors 200j (e.g., refer to the rods in FIG. 2), each semiconductor rod 205 having a base end 201 and a tip end 202, a seed 203 embedded within the j-th nanoscale semiconductor rod 200j at the base end 201, and a metal tip 204 disposed at the tip end 203 of the j-th nanoscale semiconductor rod 200j. The metal tip 204 is a co-catalyst loaded on the tip end 202 of the semiconductor rod 205, acts as a reaction site, is operable as a photocatalyst capable of catalyzing the progress of the reaction, and promotes the separation and transfer of charges driven by an interfacial junction formed between the co-catalyst and the semiconductor rod. The co-catalyst may be, for example, any metal having a relatively large work function (Φm > 4.5 eV), such as platinum (Pt), palladium (Pd), rhodium (Rh), cobalt (Co), nickel (Ni), copper (Cu), etc.

[0018] In certain exemplary implementations, the shaped nanoscale semiconductor can be of any suitable shape that enables charge separation between the seed 203 and the metal tip 204. These shapes can be, for example, at least one of a rod, a platelet, a sphere, a cube, and a core / shell semiconductor.

[0019] The removable transparent film used in the disclosed systems and the methods implemented in these systems is a transparent mesh filter sized and configured to increase the surface area exposing a plurality of shaped nanoscale semiconductors 200j. The mesh may be a mesh screen having a nominal mesh size of about 210 μM (size 70) to about 5,000 μM, depending on the size and spatial configuration of the shaped nanoscale semiconductors 200j.

[0020] In addition, the shaped nanoscale semiconductors 200j can be adsorbed directly onto particles such as silica particles and suspended in a continuously flowing mixture of water and, for example, benzaldehyde. As shown in FIG. 1, the filter 106 can be disposed downstream of the first outlet 103 as well as the second outlet 104 and sized and configured to block the flow of carrier particles 2000p (not shown). The carrier particles 2000p can be, for example, silica particles or glass beads (about 450 μm) having an average volume mean diameter (D 3,2 ) of about 10 μm to about 500 μm when measured, for example, by laser scattering. The particles can be adsorbed, for example, onto glass beads or partially embedded within the pores of silica beads (interchangeable with "particles"). The porous particles can have an average pore diameter of about 0.5 nm (5 angstroms A) to about 50 nm when measured, for example, by a helium pycnometer.

[0021] In the context of the present disclosure, the terms "transparent" or "partially transparent" refer to a wall or any other composition that allows at least 70% light transmission. The light referred to can be, for example, sunlight (with or without a filter), actinic rays (e.g., from a laser), emitted light (e.g., from a fluorescent dye), light in a given wavelength range, or a combination of the foregoing, or when measured spectrophotometrically using water (100% transmittance) as a standard at 690 nm, it can have a transmittance of at least 80%, for example at least 85%, or at least 90%. As used herein, the term "transparent" also refers to a composition that transmits at least 70% in the region of the range from 330 nm to 800 nm and has a haze of less than 10%. Similarly, the term "wall", which may be interchangeable with the term "aspect", can be used throughout to identify various layers regardless of thickness and can be a rigid body made from thermoplastic materials, silicone glass, or other glassy and / or crystalline minerals and polymers.

[0022] In an exemplary implementation, a predetermined amount of semiconductor rods 200j, and a predetermined amount of thermoplastic polymers, copolymers, terpolymers, and combinations thereof, such as poly(acrylonitrile) (PAN), poly(carbonate) (PC), poly(siloxane) (PS), poly(dimethylsiloxane) (PDMS), their copolymers, terpolymers and / or combinations, etc., are respectively suspended and dissolved in a predetermined amount of organic solvents (e.g., dimethyl furfural (DMF), acetone, diisopropylamine, triethylamine, pentane, and xylene). Next, the suspension is stirred for a predetermined time to ensure complete dissolution of all thermoplastic polymers, copolymers, terpolymers, and combinations thereof and to ensure sufficient dispersion of the semiconductor rods 200j to form a homogeneous suspension. Then, the suspension can be cast (e.g., onto glass) (or in other examples, spun / extruded), and the solvent can be removed (or in the case of spinning, woven, and in the case of extrusion, cooled) to form a sieve. Further, the loading of the shaped nanoscale semiconductor 200j into the thermoplastic polymers, copolymers, terpolymers, and / or combinations thereof is configured in an exemplary implementation to provide optimal conversion.

[0023] Thus, in another exemplary implementation, provided herein is a transparent film 105i, where each i-th removable transparent film 105i includes a plurality of at least partially embedded shaped nanoscale semiconductors 200j, each j-th semiconductor rod 200j has a proximal end 201 and a distal end 202, a seed 203 is embedded within each j-th shaped nanoscale semiconductor 200j at the proximal end 201, and a metal tip 204 is disposed at the distal end 202 of the j-th shaped nanoscale semiconductor 200j.

[0024] As shown in FIG. 2, when each j-th shaped nanoscale semiconductor 200j is a rod, it defines a longitudinal axis X L and has a length "L" parallel to the longitudinal axis X of about 25 nm to about 75 nm adapted based on the composition of each j-th semiconductor rod 200j and is capable of separating charges (electrons to the metal tip 204 and holes to the seed 203). Thus, in an exemplary implementation, the seed 203 can be a first cadmium chalcogenide (e.g., cadmium selenide (CdSe) and cadmium telluride (CdTe)), and each j-th semiconductor rod 200j is formed from at least one of a second cadmium chalcogenide (e.g., cadmium sulfide (CdS) and cadmium telluride (CdTe)), and titanium dioxide (TiO2). L Furthermore, in the context of the present disclosure, the term "semiconductor" refers to a material having a conductivity intermediate between that of a conductor and an insulator. The semiconductor may be an intrinsic semiconductor, an n-type semiconductor, or a p-type semiconductor. Examples of semiconductors include oxides of perovskite, titanium, niobium, tin, zinc, cadmium, copper, or lead, chalcogenides of antimony, copper, zinc, iron, or bismuth (e.g., copper sulfide and iron sulfide), copper zinc tin chalcogenides, such as copper zinc tin sulfides like Cu2ZnSnS4 (CZTS) and Cu2ZnSn(S

[0025] Se 1-x Se x)Copper zinc tin sulfide selenide such as 4(CZTSSe), copper indium chalcogenide such as copper indium selenide (CIS), copper indium gallium chalcogenide such as copper indium gallium selenide (CuIn 1-x Ga x Se2)(CIGS), and the like, and copper indium gallium diselenide. Further examples include group IV compound semiconductors (e.g., silicon carbide), III-V semiconductors (e.g., gallium arsenide), II-VI semiconductors (e.g., cadmium selenide), I-VII semiconductors (e.g., cuprous chloride), IV-VI semiconductors (e.g., lead selenide), V-VI semiconductors (e.g., bismuth telluride), and II-V semiconductors (e.g., cadmium hydride), ternary or quaternary semiconductors (e.g., copper indium selenide, copper indium gallium diselenide, copper zinc tin sulfide, or copper zinc tin sulfide selenide (CZTSSe)).

[0026] In an exemplary implementation, each j-th shaped nanoscale semiconductor (e.g., rod) 200j is formed from a hybrid CdS / MO, where MO is a metal oxide such as Bi2O3 (e.g., α-type lattice), In2O3, ZnO, SnO2, TiO2. In metal oxide semiconductors, native point defects (referring to 0-dimensional lattice defects of impurity atoms, vacancies, and self-interstitial atoms in pure metals) act as donors or acceptors. However, in many cases, the bandgap of metal oxides is wide and the defect levels are too deep to provide a high concentration of carriers. That is, although it is photosensitive and relatively non-toxic, the main defect of TiO2 is its wide bandgap (3.2 eV), and it is active only under UV light, which is <5% of the total solar radiation spectrum. Conversely, cadmium sulfide (CdS) absorbs in the visible region with a narrow direct bandgap of 2.4 eV, but it is known to leach Cd 2+ ions, which are toxic and reduce the quantum efficiency. Therefore, the hybrid CdS / TiO2 semiconductor rod 200j having at least one seed of cadmium selenide (CdSe) and cadmium telluride (CdTe) contains Cd 2+It is proposed to reduce the ion dropout and increase the average time during membrane exchange.

[0027] Hybrid semiconductor / metal oxide composites are designed in exemplary implementations at the molecular scale that allow for precise control of functionality, including photophysical, electrochemical, and catalytic properties. For example, p-type (orbital type) metal sulfides and CoO that act as reducing photocatalyst and oxidizing photocatalyst, respectively x Using supported BiVO4, reduction under visible light can be achieved using water as an electron donor.

[0028] Returning to FIG. 1, the hydrogen container 150 of the system 10 is in liquid communication with the first outlet 103, and the benzylamine container 160 is in liquid communication with the second outlet 104.

[0029] In certain exemplary implementations, the disclosed method is implemented in the disclosed system. Accordingly, a method for continuously generating hydrogen is provided herein. The method is a system comprising a transparent container having a first inlet and a second inlet, and a first outlet and a second outlet, a pressurized water source in liquid communication with the first inlet, a pressurized source of benzylamine in liquid communication with the second inlet, and at least one removable transparent film comprising a plurality of at least partially embedded shaped nanoscale semiconductors, each having a proximal end and a distal end, a seed embedded within the shaped nanoscale semiconductor at the proximal end, and a metal tip disposed at the distal end of the shaped nanoscale semiconductor. The method is implemented in the system and comprises filling the transparent container with water using the first inlet, exposing the transparent container to at least one of sunlight (with or without a filter), actinic radiation (e.g., from a laser), luminescent light (e.g., from a fluorescent dye), light within a given wavelength range, and combinations thereof, photocatalyzing the water using the plurality of shaped nanoscale semiconductors to form hydrogen, oxygen, and depleted water, contacting the container with benzylaldehyde in the presence of a nitrogen source using the second inlet, collecting the hydrogen using the first outlet, and removing the depleted water using the second outlet. Thereafter, periodically, if it is determined that the conversion efficiency η has decreased, i.e., when the half-reaction has a conversion efficiency of less than, for example, 61% as measured as described in Equation 1, at least one removable transparent film 105i is replaced.

[0030]

Number

[0031] Similarly, as shown in FIG. 3, the disclosed system can be used to generate benzaldehyde. As shown, this reaction converts benzylamine introduced under pressure to benzaldehyde as follows: first, benzylamine (BnNH2) is selectively converted to benzylidene benzylamine, and then, in the presence of water, hydrolysis of benzylidene benzylamine to its components, namely benzaldehyde and benzylamine, is promoted. Continuous irradiation results in further oxidation of newly formed BnNH2 and shifts the reaction balance from equilibrium towards the accumulation of benzaldehyde. Thus, in certain implementations, this reaction can be used to remove oxygen from the split water that can adversely affect the shaped nanoscale semiconductor. In certain implementations, benzylamine can be used, for example, for chemical synthesis, pesticides, polymer auxiliaries, and the manufacture of pharmaceutical substances. Accordingly, a method for continuously generating benzaldehyde is provided herein, the method being implemented in a system comprising a transparent container having a first inlet and a second inlet and a first outlet and a second outlet, a pressurized water source in liquid communication with the first inlet, a pressurized source of benzylamine in liquid communication with the second inlet, at least one removable transparent film comprising a plurality of at least partially embedded shaped nanoscale semiconductors, each having a proximal end and a distal end, a seed being embedded in the shaped nanoscale semiconductor at the proximal end, and a metal tip being disposed at the distal end of the shaped nanoscale semiconductor, the method comprising filling the transparent container with water using the first inlet, exposing the transparent container (continuously) to at least one of sunlight, actinic radiation, synchrotron radiation, light in a given wavelength range, and combinations thereof, photocatalyzing the water using the plurality of shaped nanoscale semiconductors to form hydrogen, oxygen, and depleted water, contacting the container with benzylamine (BnNH2) in the presence of a nitrogen source using the second inlet, collecting the hydrogen using the first outlet, removing the depleted water using the second outlet, and separating the accumulated benzaldehyde from the depleted water.

[0032] In an exemplary implementation, the hydrogen collected from the first outlet is further purified and compressed to a predetermined pressure (e.g., about 150 psi to 500 psi) using a gas treatment module included in the system. The gas treatment module can include a compressor, a separator, and a purifier, and in another example, is used to condition the hydrogen. For example, a heat exchanger / condenser included in the gas treatment module is used to cool the gas stream to a predetermined temperature (e.g., about 24 °C to about 45 °C), thereby removing water vapor and reducing the flow rate to the compressor. For example, a triple pump compressor with intercooling is selected in an exemplary implementation of the compressor. Additionally, the system can further include a plurality of sensors such as thermocouples, oxygen sensors, pressure sensors, flow meters, etc., and can be operably coupled to a central processing module operable to control various method steps.

[0033] As used herein, the term "comprising" and its derivatives are intended to be open - ended terms that specify the presence of the recited features, elements, components, groups, integers, and / or steps, but do not preclude the presence of other unrecited features, elements, components, groups, integers, and / or steps. The foregoing is also applicable to words having similar meanings such as the terms "including", "having", and their derivatives.

[0034] All ranges disclosed herein include their endpoints, and the endpoints are combinable independently of each other. "Combinations" include blends, mixtures, alloys, reaction products, and the like. As used herein, the terms "a," "an," and "the" are not intended to indicate a limitation of quantity and are to be construed as including both the singular and the plural unless specifically stated otherwise herein or clearly contradicted by context. The suffix "(s)" as used herein is intended to include both the singular and the plural of the term it modifies, thereby including one or more of that term (e.g., rods(s) includes one or more rods). Throughout the specification, references to "one exemplary implementation," "another exemplary implementation," "exemplary implementations," etc., if present, mean that the particular elements (e.g., features, structures, and / or characteristics) described in connection with the exemplary implementation are included in at least one exemplary implementation described herein, and may or may not be present in other exemplary implementations. Additionally, it is to be understood that the described elements may be combined in any suitable manner in the exemplary implementations.

[0035] In the context of the present disclosure, the term "operable" means that a system and / or device and / or program, or a particular element or step, when activated, coupled, implemented, actuated, brought about, realized, or when an executable program executed by at least one processor associated with the system and / or device, fully functions, is sized, adapted, and calibrated, includes and meets the elements for the applicable operating requirements for performing the recited functions. For systems and circuits, the term "operable" means that when executed by at least one processor, the system and / or circuit fully functions and is calibrated, includes the logic with the necessary hardware and firmware for the applicable operating requirements for performing the recited functions, and includes the circuitry therefor and meets that.

[0036] All ranges disclosed in this specification include endpoints, and the endpoints can be combined independently of each other. Further, terms such as "first", "second", etc. in this specification are not used to indicate any order, quantity, or importance, but are used to distinguish one element from another.

[0037] Similarly, the term "about" means a quantity, size, formulation, parameter, and means that other quantities and characteristics are not exact and that it is not necessary, but, if desired, reflects allowable ranges, conversion factors, rounding, measurement errors, etc., and other factors known to those skilled in the art, and may be approximate and / or larger or smaller. Generally, a quantity, size, formulation, parameter, or other quantity or characteristic is "about" or "approximately", whether or not so stated.

[0038] Accordingly, a system for continuously generating hydrogen by sunlight is provided herein, the system comprising a partially transparent container having an inlet(s) and an outlet, a pressurized water source in continuous liquid communication with the inlet, a pressurized source of an electron donor in liquid communication with the inlet, and a membrane or substrate comprising a plurality of at least partially embedded or fixed shaped nanoscale semiconductor particles, wherein (i) the membrane is composed of beads (e.g., silica, glass, thermoplastic), (ii) the membrane is partially or completely removable, (iii) the embedded or fixed shaped nanoscale semiconductor particles are removable (i.e., independent from the carrier / substrate / membrane), (iv) the membrane is operable as a photosensitizer, as a chemical stabilizer (referring to the ability of a material to perform photoinduced charge generation, light emission or field emission), or as an improver of the stability of the shaped nanoscale semiconductor particles, (v) the shaped nanoscale semiconductor particles comprise at least two different semiconductors having a band arrangement that supports a closed redox cycle, (vi) an additional cocatalyst domain is operable to affect charge separation, acts as a catalytic site, and reduces the activation potential of a redox half-reaction, (vii) the shape of (the shaped nanoscale semiconductor particles) is at least one of rod, wire, platelet, sheet, sphere, cube, tetrapod type, multipod type, and core-shell semiconductor shape, (viii) the size of the shaped nanoscale semiconductor is from about 2 nanometers (nm) to about 100 nm, (ix) at least one shaped nanoscale semiconductor has a bandgap and an electron affinity suitable for supporting the production of hydrogen from water by visible light, (x) is a cadmium chalcogenide, (xi) the cocatalyst is nickel, platinum, a bimetallic cocatalyst, or a transition metal chalcogenide, (xii) the first cadmium chalcogenide is at least one of cadmium selenide (CdSe) and cadmium sulfide (CdS), and the system further comprises (xiii) a hydrogen container in communication with the outlet and a container for the oxidized electron donor in communication with the outlet.

[0039] In another exemplary implementation, a method for continuously generating hydrogen is provided herein. The method is implemented in a system that includes a transparent container having a first inlet and a second inlet, and a first outlet and a second outlet, a pressurized water source in continuous liquid communication with the first inlet, a pressurized source of benzylamine in liquid communication with the second inlet, and at least one removable transparent film that includes a plurality of at least partially embedded shaped nanoscale semiconductors, each shaped nanoscale semiconductor having a base end and a tip end, a seed embedded within each of the shaped nanoscale semiconductors at the base end, and a metal tip disposed at the tip end of each of the shaped nanoscale semiconductors. The method includes filling the transparent container continuously (in a continuous flow) with water using the first inlet, exposing the transparent container to at least one of sunlight, actinic radiation, radiant light, light in a given wavelength range, and combinations thereof, photocatalyzing the water using the plurality of shaped nanoscale semiconductors to produce hydrogen, oxygen, and depleted water, contacting the container with benzylamine (BnNH2) in the presence of a nitrogen source using the second inlet, collecting the hydrogen using the first outlet, and continuously removing the depleted water using the second outlet. The method further includes (xiv) periodically removing at least one removable transparent film or beads, and replacing the removable transparent film or beads with an unexposed removable transparent film or unexposed beads to which shaped adsorbed or partially embedded shaped nanoscale semiconductors(s) are attached.

[0040] In yet another exemplary implementation, a method for continuously generating benzaldehyde is provided herein. The method is implemented in a system that includes a transparent container having a first inlet, a second inlet, a first outlet, and a second outlet; a pressurized water source in liquid communication with the first inlet; a pressurized source of benzylamine (BnNH2) in liquid communication with the second inlet; and at least one removable transparent membrane or a plurality of beads, each including a plurality of at least partially embedded shaped nanoscale semiconductors, each shaped nanoscale semiconductor having a base end and a tip end, a seed embedded within each shaped nanoscale semiconductor at the base end, and a metal tip disposed at the tip end of each shaped nanoscale semiconductor. The method includes continuously filling the transparent container with water using the first inlet; exposing the transparent container to at least one of sunlight, actinic radiation, synchrotron radiation, light within a given wavelength range, and combinations thereof; photocatalyzing the water using the plurality of shaped nanoscale semiconductors to produce hydrogen, oxygen, and depleted water; contacting the container with benzylamine (BnNH2) in the presence of a nitrogen source using the second inlet; collecting the hydrogen using the first outlet; removing the depleted water using the second outlet; and separating the accumulated benzaldehyde from the depleted water. The method further includes (xv) periodically (e.g., when determined to be appropriate, e.g., when detecting a decrease in hydrogen production exceeding 5%, or 10%, or 20%, or 30% from initial hydrogen production), removing at least a portion of the at least one removable transparent membrane or the plurality of beads, and replacing the removed portion of the removable transparent membrane or the plurality of beads with an unexposed removable transparent membrane or an unexposed portion of the plurality of beads having shaped nanoscale semiconductors (s) (plural) that are shaped and adsorbed or partially embedded and bonded thereto.

[0041] The above embodiments and descriptions are, of course, provided for illustrative purposes only and are in no way intended to limit the disclosed technology. As will be understood by those skilled in the art, the disclosed technology can be carried out in a very variety of ways by adopting two or more techniques from those described above, without exceeding the scope of the present invention at all.

Claims

1. A system for continuously generating hydrogen by sunlight, comprising: a) a partially transparent container having an inlet(s) and an outlet; b) a pressurized water source in continuous liquid communication with the inlet; c) a pressurized source of an electron donor in liquid communication with the inlet; d) a membrane or substrate comprising a plurality of at least partially embedded or fixed shaped nanoscale semiconductor particles.

2. The system according to claim 1, wherein the membrane is a transparent mesh filter.

3. The system according to claim 1, wherein the membrane consists of beads.

4. The system according to claim 3, wherein the membrane is partially or completely removable.

5. The system according to claim 1, wherein the embedded or fixed shaped nanoscale semiconductor particles are removable.

6. The system according to claim 1, wherein the membrane is operable as a photosensitizer, as a chemical stabilizer, or as an agent for improving the stability of the shaped nanoscale semiconductor particles.

7. The system according to claim 1, wherein the shaped nanoscale semiconductor particles comprise at least two different semiconductors having a band arrangement that supports a closed redox cycle.

8. The system according to claim 1, wherein the shaped nanoscale semiconductor particles are operable to affect charge separation, function as a catalytic site, and include an additional co-catalyst domain that lowers the activation potential of a redox half-reaction.

9. The system according to claim 8, wherein the shape is at least one of a rod, wire, platelet, sheet, sphere, cube, tetrapod type, multipod type, and core / shell semiconductor.

10. The system according to claim 8, wherein the size of the shaped nanoscale semiconductor is from about 2 nanometers (nm) to about 100 nm.

11. The system according to claim 7, wherein at least one shaped nanoscale semiconductor has a band gap and an electron affinity suitable for supporting the generation of hydrogen from water by visible light.

12. The system according to claim 11, wherein at least one shaped nanoscale semiconductor is a cadmium chalcogenide.

13. The system according to claim 8, wherein the co-catalyst is nickel, platinum, a bimetallic co-catalyst, or a transition metal chalcogenide.

14. The system according to claim 12, wherein the first cadmium chalcogenide is at least one of cadmium selenide (CdSe) and cadmium sulfide (CdS).

15. a) a hydrogen container in communication with the outlet; b) a container for an oxidized electron donor in communication with the outlet, the system according to claim 1.

16. A method for continuously generating hydrogen, the method being implemented in a system comprising: a transparent container having a first inlet, a second inlet, a first outlet, and a second outlet; a pressurized water source in continuous liquid communication with the first inlet; a pressurized source of benzylamine in liquid communication with the second inlet; at least one removable transparent film comprising a plurality of at least partially embedded shaped nanoscale semiconductors, each shaped nanoscale semiconductor having a base end and a tip end, a seed being embedded within each of the shaped nanoscale semiconductors at the base end, and a metal tip being disposed at the tip end of each of the shaped nanoscale semiconductors, the method comprising: a) continuously filling the transparent container with water using the first inlet; b) exposing the transparent container to at least one of sunlight, actinic radiation, synchrotron radiation, light in a given wavelength range, and combinations thereof; c) photocatalyzing the water using the plurality of shaped nanoscale semiconductors to produce hydrogen, oxygen, and depleted water; d) using the second inlet, contacting the vessel with the benzylamine (BnNH ２ ) in the presence of a nitrogen source; e) collecting the hydrogen using the first outlet; f) removing the depleted water using the second outlet.

17. The method according to claim 16, further comprising periodically removing at least one removable transparent film and replacing the removed transparent film with an unexposed removable transparent film.

18. A method for continuously generating benzaldehyde, said method comprising a system comprising a transparent container having a first inlet and a second inlet and a first outlet and a second outlet, a pressurized water source in liquid communication with said first inlet, and a benzylamine (BnNH[[ID=I]] ２ ), a pressurized source of), at least one removable transparent film or a plurality of beads each containing a plurality of at least partially embedded shaped nanoscale semiconductors, each shaped nanoscale semiconductor having a base end and a tip end, a seed being embedded within each shaped nanoscale semiconductor at said base end, and a metal tip being disposed at said tip end of each shaped nanoscale semiconductor, a transparent film, implemented in a system, said method comprising a) continuously filling the transparent container with water using the first inlet; b) exposing the transparent container to at least one of sunlight, actinic radiation, synchrotron radiation, light in a given wavelength range, and combinations thereof; c) photocatalyzing the water using the plurality of shaped nanoscale semiconductors to produce hydrogen, oxygen, and depleted water; d) Using the second inlet, contacting the vessel with the benzylamine (BnNH ２ ) in the presence of a nitrogen source; e) collecting the hydrogen using the first outlet; f) removing the depleted water using the second outlet; g) separating the accumulated benzaldehyde from the depleted water, a method comprising.

19. removing at least one removable transparent film or at least a portion of the plurality of beads periodically, and replacing the removable transparent film or the portion of the plurality of beads with an unexposed removable transparent film or an unexposed portion of the plurality of beads to which the shaped and adsorbed or partially embedded shaped nanoscale semiconductor(s) are attached, the method of claim 18 further comprising.

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