Photoelectrochemical cell and photoelectrochemical method

Abstract

The present invention concerns a photoelectrochemical cell (1) for the photoelectrochemical decomposition of a starting material into a final product, said photoelectrochemical cell (1) comprising: - an entry line (2) for feeding the starting material; - an exit line (3) for the exit of the final product; - a first electrode (4) made of photoelectrically active material and configured to be exposed to solar radiation (S) when in use; - a second electrode (5); - an electrical conductor (6) suitable for connecting said first electrode (4) and said second electrode (5) creating a closed circuit, for the transport of electrons excited by solar radiation (S) incident on the first electrode (4), and - an ionic conductor (7) for the transport of ions produced in the decomposition of the starting material, wherein said second electrode (5) has a mesh configuration.

Description

[0001] Photoelectrochemical cell and photoelectrochemical method

[0002] Description

[0003] The present invention relates to a photoelectrochemical cell .

[0004] Preferably, the photoelectrochemical cell is intended for the decomposition of a starting material , for example water, into a final product , for example molecular hydrogen .

[0005] The present invention also relates to a photoelectrochemical method .

[0006] Preferably, the photoelectrochemical method is intended for the decomposition of a starting material , for example water, into a final product , for example molecular hydrogen .

[0007] As is well known, technological development in the photoelectrochemical sector in recent years has been geared towards the development of solar-powered systems and processes that allow products to be obtained through a lower environmental impact or to puri fy products through a lower environmental impact .

[0008] For example , various photoelectrochemical systems are known for the sunlight-activated decomposition of a starting material ( for example , water or carbon dioxide ) to obtain a product of interest ( according to the example , respectively, hydrogen or carbon monoxide ) .

[0009] Typically, such photoelectrochemical systems comprise a feed of the starting material , an exit of the final product , a first electrode that is photoelectrochemically active and exposed to sunlight during operation, and a second electrode connected to the first electrode by means of an electrical conductor .

[0010] Such known photoelectrochemical systems have several drawbacks .

[0011] A first drawback is represented by the fact that the known photoelectrochemical systems have a non-optimal ef ficiency (understood as conversion of solar energy into chemical energy by means of an electrochemical process ) , which is incompatible with an industrial production and thus invalidating their use in such contexts .

[0012] A second drawback is represented by the fact that said known photoelectrochemical systems typically have a low productivity (understood as the quantity of final product obtained in a given time interval ) , which is incompatible with an industrial production and thus invalidating their use in such contexts . The obj ect of the present invention is to provide a photoelectrochemical cell for the photoelectrochemical decomposition of a starting material ( for example water ) into a final product ( for example molecular hydrogen) that allows to obtain optimal ef ficiency and high productivity .

[0013] Furthermore , the obj ect of the present invention is to provide a method for the photoelectrochemical decomposition of a starting material ( for example water ) into a final product ( for example molecular hydrogen) that allows to obtain optimal ef ficiency and high productivity .

[0014] According to the present invention, a photoelectrochemical cell , as defined in claim 1 , is reali zed .

[0015] For a better understanding of the present invention, a preferred embodiment is now described, by way of non-limiting example only, with reference to the accompanying drawings , in which :

[0016] - figure 1 shows a schematic and perspective view of a photoelectrochemical cell , according to the invention; figure 2 shows a front section of a photoelectrochemical cell , according to the invention; figure 3 shows a schematic side view of a photoelectrochemical cell , according to the invention . With particular reference to figure 1 , the photoelectrochemical cell 1 for the photoelectrochemical decomposition of a starting material , for example water, into a final product , for example molecular hydrogen, preferably comprises an entry line 2 for feeding the starting material .

[0017] According to a preferred embodiment , the starting material is in substantially liquid phase .

[0018] Preferably, the entry line 2 comprises at least one pumping means (not illustrated) configured to pump said starting material into said photoelectrochemical cell 1 .

[0019] Said at least one pumping means is any type of known means ( for example , any type of mechanical pump ) configured to guarantee a continuous or discontinuous flow rate of the starting material in input to said photoelectrochemical cell 1 .

[0020] Preferably, said photoelectrochemical cell 1 comprises an exit line 3 for the exit of the final product .

[0021] According to a preferred embodiment , the final product may be in substantially gaseous phase or in substantially liquid phase .

[0022] Preferably, the exit line 3 comprises at least one pumping means (not illustrated) configured to pump said final product out of said photoelectrochemical cell 1 . Said at least one pumping means is any type of known means ( for example , any type of mechanical pump or any type of aspirator ) configured to guarantee a continuous or discontinuous flow rate of the final product in output from said photoelectrochemical cell 1 .

[0023] Preferably, said photoelectrochemical cell 1 comprises a first electrode 4 made of photoelectrically active material .

[0024] Preferably, said first electrode 4 is at least partially immersed in said starting material .

[0025] Preferably, said first electrode 4 is configured to be exposed to a solar radiation S when in use .

[0026] Preferably, said photoelectrochemical cell 1 comprises a second electrode 5 .

[0027] Preferably, said second electrode 5 is at least partially immersed in said starting material .

[0028] Preferably, as illustrated in figure 2 , said photoelectrochemical cell 1 comprises an electrical conductor 6 suitable for connecting said first electrode 4 and said second electrode 5 .

[0029] Preferably, said electrical conductor 6 creates a closed circuit , for the transport of electrons excited by the solar radiation S incident on the first electrode 4 . Said electrical conductor 6 can be made of metallic material , for example a metallic wire .

[0030] Preferably, as illustrated in figure 1 and figure 2 , said photoelectrochemical cell 1 comprises an ionic conductor 7 .

[0031] Preferably, said ionic conductor 7 is configured to transport the ions produced in the decomposition of the starting material .

[0032] Said ionic conductor 7 can be made according to a configuration and / or made of materials as provided by any ionic conductor used in electrochemical cells . An example of such an ionic conductor 7 is represented by a proton-exchange membrane , such as for example a membrane comprising Nafion .

[0033] Preferably, said second electrode 5 has a mesh configuration .

[0034] Mesh configuration means a structure interlaced of substantially threadlike elements , crossed together regularly so that free spaces , called meshes , remain .

[0035] These characteristics derive from the experimental tests carried out by the Applicant , in which the Applicant tried out di f ferent alternative solutions in order to find the solution that best ensured optimal ef ficiency and high productivity . In detail , compared to the known art , one of the advantages of the photoelectrochemical cell 1 of the present invention is represented by the mesh configuration of the second electrode 5 which allows to increase the active surface of the second electrode 5 itsel f , thus allowing a greater interaction with the starting material . This entails an optimi zation of the ef ficiency and a high productivity for the photoelectrochemical cell 1 since , with the same volume of starting material , a greater active surface of the second electrode 5 allows a greater interaction with the starting material and thus a greater consequent photoelectrochemical degradation of the starting material ( and therefore a greater obtaining of the final product ) .

[0036] In addition, the mesh conformation of the second electrode 5 allows the first electrode 4 to be more exposed to solar radiation S , which allows the solar radiation S to hit on a greater surface of the first electrode 4 made of photoelectrically active material . This further contributes to the optimi zation of the ef ficiency and high productivity for the photoelectrochemical cell 1 since , with the same power of the solar radiation S , a greater exposure of the photoelectrically active surface of the first electrode 4 allows a greater interaction with the incident solar radiation S and thus a greater consequent photoelectrochemical degradation of the starting material ( and thus a greater obtaining of the final product ) .

[0037] According to a further aspect of the invention, as illustrated in figure 1 , figure 2 and figure 3 , said photoelectrochemical cell 1 has a substantially tubular conformation .

[0038] In other words , the spatial arrangement of said elements of the photoelectrochemical cell 1 allows to obtain a substantially tubular conformation . This has the advantage of obtaining a compact structure for said photoelectrochemical cell 1 .

[0039] According to said substantially tubular conformation, said entry line 2 and said exit line 3 respectively define the entry and exit of said substantially tubular conformation .

[0040] According to a further aspect of the invention, said first electrode 4 is made of a material comprising at least one metallic oxide , for example : ferric oxide doped with titanium; tungsten trioxide .

[0041] This characteristic derives from the experimental tests carried out by the Applicant , in which the Applicant tried out di f ferent alternative solutions in order to find the solution that best ensured optimal ef ficiency and high productivity . In particular, the use of at least one metallic oxide for the first electrode 4 allows to maximi ze the photoelectric activity of the first electrode 4 itsel f , ensuring optimal ef ficiency and high productivity .

[0042] According to a preferred embodiment , said at least one metallic oxide can be ferric oxide doped with titanium and / or tungsten trioxide , which were found to be , from the experimental tests carried out by the Applicant , the metallic oxides that maximi ze the photoelectric activity of the first electrode 4 .

[0043] According to a further aspect of the invention, said second electrode 5 is made of a material comprising a catalytically active material , for example nickel .

[0044] This characteristic derives from the experimental tests carried out by the Applicant , in which the Applicant tried out di f ferent alternative solutions in order to find the solution that best ensured optimal ef ficiency and high productivity .

[0045] In particular, the use of at least one catalytically active material for the second electrode 5 allows to maximi ze the photoelectrochemical degradation activity of the starting material that occurs at the second electrode 5 itsel f , ensuring optimal ef ficiency and high productivity . According to a preferred embodiment, said at least one catalytically active material can be nickel, which has been found to be, from the experimental tests carried out by the Applicant, the catalytically active material that maximizes the electrochemical degradation activity of the second electrode 5.

[0046] According to a further aspect of the invention, said first electrode 4 is a photoanode and said second electrode 5 is a cathode.

[0047] This characteristic derives from the experimental tests carried out by the Applicant, in which the Applicant tried out different alternative solutions in order to find the solution that best ensured optimal efficiency and high productivity .

[0048] According to this preferred configuration, the solar radiation S hits on said first electrode 4 made of photoelectrically active material, i.e. the photoanode, causing the transition of the electrons of said first electrode 4 into an excited state; said excited electrons are transported through said electrical conductor 6 to the second electrode 5, i.e. the cathode, creating a closed circuit. Said photoelectrochemical process results in the electrochemical oxidation of the starting material at the first electrode 4, i.e. the photoanode, and the electrochemical reduction of the starting material at the second electrode 5 , i . e . the cathode ; according to said photoelectrochemical process , said ionic conductor 7 is necessary for the transport of the ions produced in the decomposition of the starting material , in particular for the transport of said ions from the second electrode 5 ( the cathode ) towards the first electrode 4 ( the photoanode ) .

[0049] According to a preferred embodiment , the starting material is represented by water in substantially liquid phase . The photoelectrochemical process described makes it possible to obtain as the final product a mixture of molecular hydrogen in the substantially gaseous phase and molecular oxygen in the substantially gaseous phase ( in addition to any water not converted into the substantially liquid phase ) .

[0050] Said photoelectrochemical process is defined by photoelectrochemical redox reactions ( i . e . photoinduced electrochemical redox ) which provide the photoinduced electrochemical degradation of water into molecular hydrogen and molecular oxygen . Such reactions are fully known from the state of the art for said known photoelectrochemical systems .

[0051] Molecular hydrogen is generated at the electrode on which the electrochemical reduction of water takes place , while molecular oxygen is generated at the electrode on which the electrochemical oxidation of water takes place .

[0052] According to said preferred embodiment wherein the first electrode 4 is the photoanode and the second electrode 5 is the cathode , the molecular hydrogen is generated at the second electrode 5 , while the molecular oxygen is generated at the first electrode 4 .

[0053] Advantageously, the molecular hydrogen generated is the final product of greatest interest , as it is generated with high ef ficiency and productivity, in a manner with low environmental impact ( especially in relation to the known industrial processes of molecular hydrogen generation) and for the various uses in the industrial field and in the transports in which it is used .

[0054] According to a further aspect of the invention, as illustrated in figure 1 , figure 2 and figure 3 , said photoelectrochemical cell 1 is comprised inside a container body 8 having a first semi-unit 9 made of material transparent to solar radiation S and a second semi-unit 10 made of metallic material .

[0055] Preferably, said container body 8 is configured to define said entry line 2 and said exit line 3 .

[0056] These characteristics derive from the experimental tests carried out by the Applicant , in which the Applicant tried out di f ferent alternative solutions in order to find the solution that best ensured optimal ef ficiency and high productivity .

[0057] In particular, the use of the container body 8 in which the photoelectrochemical cell 1 is arranged, allows to obtain a compact configuration for the photoelectrochemical cell 1 itsel f .

[0058] Furthermore , this configuration allows to feed said starting material directly at each electrode , given the compact dimensions of the photoelectrochemical cell 1 according to this configuration; in other words , said container body 8 is preferably configured to define said entry line 2 and said exit line 3 .

[0059] Furthermore , the substantially tubular configuration of the photoelectrochemical cell 1 favours its insertion inside the container body 8 .

[0060] Preferably, said container body 8 has a substantially tubular configuration . In this way, the container body 8 is able to contain said photoelectrochemical cell 1 even more ef fectively .

[0061] In detail , the presence of said first semi-unit 9 made of material transparent to solar radiation S allows to optimi ze the exposure of the photoelectrochemical cell 1 to solar radiation S , and in particular allows to optimi ze the exposure of the first photoelectrically active electrode 4 to solar radiation S , which allows to optimi ze the ef ficiency and productivity of the photoelectrochemical cell 1 .

[0062] According to a preferred embodiment , said first semiunit 9 is made of a material comprising any type of glass .

[0063] In addition, the second semi-unit 10 is made of any metallic material since this material , unlike other materials experimentally tested by the Applicant , allows to ef fectively confine , in the photoelectrochemical cell 1 , the solar radiation S entered through the first semi-unit 9 , which entails a further increase of the solar radiation S incident on the first photoelectrically active electrode 4 and therefore further contributes to optimi zing the ef ficiency and productivity of the photoelectrochemical cell 1 .

[0064] Preferably, as illustrated in figure 1 and figure 2 , said ionic conductor 7 is arranged in such a way as to divide said container body 8 into two semi-units , i . e . said first semi-unit 9 and said second semi-unit 10 .

[0065] According to a preferred embodiment , said container body 8 , containing said photoelectrochemical cell 1 , is at least partially inserted inside an external body (not illustrated) configured to at least partially contain said container body 8 . Preferably, said external body is made of a material comprising any type of glass .

[0066] Preferably, any type of gas is absent in the interstitial space between said container body 8 and said external body . In other words , the pneumatic vacuum is present in said interstitial space .

[0067] According to a further aspect of the invention, as illustrated in figure 1 and figure 2 , said first electrode 4 is deposited at at least a portion of the only internal surface of said second semi-unit 10 .

[0068] This characteristic derives from the experimental tests carried out by the Applicant , in which the Applicant tried out di f ferent alternative solutions in order to find the solution that best ensured optimal ef ficiency and high productivity .

[0069] In particular, the configuration of the first photoelectrically active electrode 4 in the form of a layer deposited at at least a portion of the only internal surface of said second semi-unit 10 , allows to obtain a compact configuration for the photoelectrochemical cell 1 .

[0070] Furthermore , this configuration for said first photoelectrically active electrode 4 entails a greater active surface thereof compared to an electrode with standard conformation; this contributes to further optimi zing the ef ficiency and increasing the productivity of the photoelectrochemical cell 1 .

[0071] According to a further aspect of the invention, as illustrated in figure 1 figure 2 , said second electrode 5 is in contact with at least a portion of the second semi-unit 10 .

[0072] In other words , said second electrode 5 is configured such that at least a portion thereof is arranged in contact with at least a portion of the second semi-unit 10 . This further contributes to obtaining a compact structure for said photoelectrochemical cell 1 .

[0073] According to a preferred embodiment , said second electrode 5 is deposited at at least a portion of the only internal surface of said second semi-unit 10 . In other words , said second electrode 5 is deposited according to said mesh configuration at a portion of the internal surface of said second semi-unit 10 , said portion being di f ferent from said at least a portion of internal surface of said second semiunit 10 on which said first electrode 4 can be deposited .

[0074] Alternatively, said second electrode 5 is in the form of a sheet according to said mesh configuration .

[0075] According to a preferred embodiment , as illustrated in figure 1 and figure 2 , said second electrode 5 is arranged in proximity to said ionic conductor 7 . This has the advantage of reducing the ionic path of the ions that are generated during the photoelectrochemical degradation process of the starting material .

[0076] According to a preferred embodiment , said photoelectrochemical cell 1 comprises a voltage generator (not illustrated) configured to apply a voltage to said first electrode 4 and said second electrode 5 when said photoelectrochemical cell 1 is in a non-operating phase .

[0077] In other words , when said photoelectrochemical cell 1 is in use , said first electrode 4 and said second electrode 5 , connected by said electrical conductor 6 to define a closed circuit , have a respective voltage defining the di f ference of potential of the photoelectrochemical cell 1 . When said photoelectrochemical cell 1 is in a non-operating condition, said voltage generator is configured to apply a respective voltage to said first electrode 4 and said second electrode 5 ; said respective applied voltage is reversed with respect to the voltage assumed by each electrode during the operating phase of the photoelectrochemical cell 1 . This entails the possibility, during a non-operating phase of the photoelectrochemical cell 1 , of reversing the flow of electrons between the two electrodes ( along said electrical conductor 6 ) which entails the possibility of cleaning the surface of said first electrode 4 and said second electrode

[0078] 5 .

[0079] In summary, said voltage generator allows to reverse the voltage of each electrode of the photoelectrochemical cell 1 , which entails the possibility of cleaning said first electrode 4 and said second electrode 5 .

[0080] In particular, said voltage generator can be any device configured to apply a di f ference of potential to two electrodes , for example an electric cell or an electric battery .

[0081] Said voltage generator may be arranged inside the photoelectrochemical cell 1 .

[0082] Alternatively, said voltage generator may be arranged externally to the photoelectrochemical cell 1 .

[0083] Said voltage generator can be arranged inside said container body 8 .

[0084] Alternatively, said voltage generator may be arranged externally to said container body 8 .

[0085] Said voltage generator may be arranged inside said external body .

[0086] Alternatively, said voltage generator may be arranged externally to said external body .

[0087] According to a further aspect of the invention, as illustrated in figure 1 , said photoelectrochemical cell 1 comprises an optical system 11 configured to concentrate the solar radiation S incident on said first electrode 4 .

[0088] This characteristic derives from the experimental tests carried out by the Applicant , in which the Applicant tried out di f ferent alternative solutions in order to find the solution that best ensured optimal ef ficiency and high productivity .

[0089] In particular, concentrating the solar radiation S incident on said first electrode 4 by means of said optical system 11 configured for this purpose , allows to increase the solar radiation S that hits on the surface of said first photoelectrically active electrode 4 , optimi zing the ef ficiency and increasing the productivity of the photoelectrochemical cell 1 .

[0090] On the basis of the experimental tests carried out by the Applicant , it has been observed that gap metallic oxidebased photoelectrodes for the photoelectrochemical cleavage of water, such as hematite (a-Fe20s ) , respond linearly to the incident solar irradiance , producing up to 20 mA / cm2of electric current with a concentration factor of 10 suns .

[0091] In particular, on the basis of the experimental tests carried out by the Applicant , graph 1 is reported below which illustrates the trend of the intensity of electric current produced as a function of the irradiation of solar radiation S on said photoelectrically active electrode according to the present invention :

[0092] Graph 1

[0093] As indicated by the reported graph 1 , it has been observed that high gap metallic oxide-based photoelectrodes for photoelectrochemical cleavage of water according to the invention, such as hematite (a-Fe20s ) , respond linearly to incident solar irradiance . In detail , the intensity of current produced is a linear function of the irradiation of the solar radiation S on said photoelectrically active electrode according to the present invention; for a concentration factor of 1 sun, about 2mA / cm2of electric current are produced, up to generating 20 mA / cm2of electric current for a concentration factor of 10 suns .

[0094] Said optical system 11 can be arranged inside the photoelectrochemical cell 1 .

[0095] Alternatively, said optical system 11 can be arranged externally to the photoelectrochemical cell 1 .

[0096] Said optical system 11 can be arranged inside said container body 8 .

[0097] Alternatively, said optical system 11 can be arranged externally to said container body 8 .

[0098] Said optical system 11 can be arranged inside said external body .

[0099] Alternatively, said optical system 11 may be arranged externally to said external body .

[0100] According to a preferred embodiment , said optical system 11 is a system comprising at least one parabolic solar mirror . Such a parabolic configuration of said at least one parabolic solar mirror allows an optimal ef fect of concentration of the solar radiation S that hits on said first electrode 4 , further contributing to optimi zing the ef ficiency and increasing the productivity of the photoelectrochemical cell 1 . According to a further aspect of the invention, the method for the photoelectrochemical decomposition of a starting material , for example water, into a final product , for example molecular hydrogen, comprises a step of feeding the starting material to said first electrode 4 made of photoelectrically active material and / or to said second electrode 5 .

[0101] According to a preferred embodiment , the starting material is in substantially liquid phase .

[0102] Said feeding step may comprise a sub-step of pumping said starting material to said first electrode 4 .

[0103] Preferably, said method comprises a step of exposing said first electrode 4 to solar radiation S incident on said first electrode 4 , generating excited electrons .

[0104] Preferably, said method comprises a step of transporting said excited electrons , which decompose the starting material , to the second electrode 5 .

[0105] Preferably, said transporting step takes place by means of an electrical conductor 6 generating a closed circuit .

[0106] Said electrical conductor 6 can be made of metallic material , for example a metallic wire .

[0107] Preferably, said method comprises a step of transporting the ions produced in the decomposition of the starting material towards the other respective first electrode 4 or second electrode 5 .

[0108] Preferably, said transporting step takes place by means of an ionic conductor 7 .

[0109] Said ionic conductor 7 can be made according to a configuration and / or made of materials as provided by any ionic conductor used in electrochemical cells . An example of such an ionic conductor 7 is represented by a proton-exchange membrane , such as for example a membrane comprising Nafion .

[0110] Preferably, said method comprises a step of collecting the final product at the exit .

[0111] According to a preferred embodiment , the final product may be in substantially gaseous phase or in substantially liquid phase .

[0112] Preferably, said collection step comprises a sub-step of pumping said final product out of said photoelectrochemical cell 1 .

[0113] Said method comprises a step of providing said second electrode 5 in a mesh configuration .

[0114] Mesh configuration means a structure interlaced of substantially threadlike elements , crossed together regularly so that free spaces , called meshes , remain .

[0115] These characteristics derive from the experimental tests carried out by the Applicant , in which the Applicant tried out di f ferent alternative solutions in order to find the solution that best ensured optimal ef ficiency and high productivity .

[0116] In detail , compared to the known art , one of the advantages of the photoelectrochemical decomposition method of the present invention is represented by the mesh configuration of the second electrode 5 that allows to increase the active surface of the second electrode 5 itsel f , thus allowing a greater interaction with the starting material . This entails an optimi zation of the ef ficiency and a high productivity since , with the same volume of starting material , a greater active surface of the second electrode 5 allows a greater interaction with the starting material and thus a greater consequent photoelectrochemical degradation of the starting material ( and therefore a greater obtaining of the final product ) .

[0117] In addition, the mesh conformation of the second electrode 5 allows the first electrode 4 to be more exposed to solar radiation S , which allows the solar radiation S to hit on a greater surface of the first electrode 4 made of photoelectrically active material . This further contributes to the optimi zation of ef ficiency and high productivity since , with the same power of the solar radiation S , a greater exposure of the photoelectrically active surface of the first electrode 4 allows a greater interaction with the incident solar radiation S and thus a greater consequent photoelectrochemical degradation of the starting material ( and thus a greater obtaining of the final product ) . All the characteristics of the photoelectrochemical cell and of the method for the photoelectrochemical decomposition derive from experimental tests carried out by the Applicant , in which the Applicant tried out di f ferent alternative solutions , in order to find the solution that best ensured optimal ef ficiency and high productivity .

[0118] Finally, it is clear that modi fications and variations can be made to the photoelectrochemical cell and the relative method for the photoelectrochemical decomposition, described and illustrated herein, without departing from the protective scope of the present invention, as defined in the appended claims .

Claims

CLAIMS1. Photoelectrochemical cell (1) for the photoelectrochemical decomposition of a starting material, for example water, into a final product, for example molecular hydrogen, said photoelectrochemical cell (1) comprising :- an entry line (2) for feeding the starting material;- an exit line (3) for the exit of the final product;- a first electrode (4) made of photoelectrically active material and configured to be exposed to solar radiation (S) when in use;- a second electrode (5) ;- an electrical conductor (6) suitable for connecting said first electrode (4) and said second electrode (5) creating a closed circuit, for the transport of electrons excited by solar radiation (S) incident on the first electrode (4) , and- an ionic conductor (7) for the transport of ions produced in the decomposition of the starting material, wherein said second electrode (5) has a mesh configuration .

2. Photoelectrochemical cell (1) according to the preceding claim, wherein said cell has a substantially tubular shape.

3. Photoelectrochemical cell (1) according to one or more of the preceding claims, wherein said first electrode(4) is made of a material comprising at least one metallic oxide, for example: ferric oxide doped with titanium; tungsten trioxide.

4. Photoelectrochemical cell (1) according to one or more of the preceding claims, wherein said second electrode(5) is made of a material comprising a catalytically active material, for example nickel.

5. Photoelectrochemical cell (1) according to one or more of the preceding claims, wherein said first electrode (4) is a photoanode and said second electrode (5) is a cathode .

6. Photoelectrochemical cell (1) according to one or more of the preceding claims, wherein said cell is comprised inside a container body (8) having a first semi-unit (9) made of material transparent to solar radiation (S) and asecond semi-unit (10) made of metallic material, said container body (8) being configured to define said entry line (2) and said exit line (3) .

7. Photoelectrochemical cell (1) according to claim 6, wherein said first electrode (4) is deposited at at least a portion of the only internal surface of said second semiunit (10) .

8. Photoelectrochemical cell (1) according to claim 6 or 7, wherein the second electrode (5) is in contact with at least a portion of the second semi-unit (10) .

9. Photoelectrochemical cell (1) according to one or more of the preceding claims, wherein said cell comprises an optical system (11) configured to concentrate the solar radiation (S) incident on said first electrode (4) .

10. Method for the photoelectrochemical decomposition of a starting material, for example water, into a final product, for example molecular hydrogen, said method comprising the following steps:- feeding the starting material to a first electrode(4) made of photoelectrically active material and / or to a second electrode (5) ;- exposing said first electrode (4) to solar radiation(5) incident on said first electrode (4) , generating excited electrons ;- transporting said excited electrons, which decompose the starting material, to the second electrode (5) by means of an electric conductor (6) , generating a closed circuit;- transporting, by means of an ionic conductor (7) , the ions produced in the decomposition of the starting material towards the other respective first electrode (4) or second electrode ( 5 ) ;- collecting the final product at the exit, wherein the method comprises a step of providing said second electrode (5) according to a mesh configuration.

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