Perovskite Oxide Semiconductor for Visible Light Water Splitting
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Solution Overview
Problem
There is a lack of effective photocatalytic materials that can decompose water into hydrogen and oxygen using visible light, with most materials requiring ultraviolet radiation and being costly, such as Ta3N5 and Ag3VO4, which are nitride and silver-based, posing a challenge in terms of cost and efficiency.
Innovation Solution
A hydrogen and oxygen producing device utilizing a perovskite oxide-based optically pumped semiconductor with a composition of BaZr0.8Gd0.2O3-α or BaZr0.8Ga0.2O3-α, capable of absorbing visible light with a wavelength of 460 nm or more, which is synthesized using a high temperature solid phase reaction method, allowing for efficient decomposition of water into hydrogen and oxygen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional photocatalytic materials (Ta3N5, Ag3VO4) are used to achieve visible light absorption, then photocatalytic activity is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive photocatalytic materials (Ta3N5, Ag3VO4) with a cost-effective alternative: a semiconductor crystal containing Ba, Zr, and In elements. This substitution maintains visible light absorption capability while significantly reducing manufacturing cost, aligning with the principle of using cheaper materials to achieve the same functional outcome.
Solution Approach 2:
The patent optimizes the semiconductor crystal's compositional parameters (Ba, Zr, In ratios) and structural parameters (lattice constants a, b, c within specific ranges, a/c ratio ≥ 0.98) to enhance visible light absorption. By adjusting these parameters, the material achieves high photocatalytic activity without requiring expensive conventional photocatalysts.
2Reliability
If anatase titanium oxide is used as photocatalyst, then photocatalytic activity is achieved, but solar-to-hydrogen conversion efficiency remains low at about 0.5%
Solution Approach 1:
The patent fundamentally changes the material parameters by transitioning from anatase titanium oxide to a Ba-Zr-In semiconductor crystal with specific compositional ratios and lattice parameters. This parameter change enables the material to absorb visible light more effectively, thereby significantly improving solar-to-hydrogen conversion efficiency while maintaining reliable photocatalytic activity.
Solution Approach 2:
The patent employs a composite semiconductor crystal incorporating multiple elements (Ba, Zr, In) in specific proportions. This composite structure synergistically enhances both visible light absorption and photocatalytic water decomposition efficiency, overcoming the limitations of single-element anatase titanium oxide.
3Device complexity
If powder type photocatalytic system is used, then structural simplicity is achieved, but separation of hydrogen and oxygen becomes difficult thereby lowering efficiency
Solution Approach 1:
The patent introduces a separation film as an intermediary component in the photocatalytic system. This film is positioned between the powder photocatalyst and the collection system to facilitate efficient separation of hydrogen and oxygen gases while maintaining the structural simplicity of the powder-type configuration. The separation film acts as a selective barrier that allows gas passage while preventing mixing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The optically pumped semiconductor achieves high efficiency in producing hydrogen and oxygen using visible light, offering a cost-effective solution with improved photocatalytic performance and stability, suitable for use in solar cells and water purification devices.
Implementation Method 1
a quartz cell (8) formed of a material that allows the light emitted from the light source to transmit therethrough and adapted to hold a dispersion (7) of water and a powder of an optically pumped semiconductor for decomposing water and thereby producing hydrogen and/or oxygen when being irradiated with light
Implementation Method 2
the optically pumped semiconductor has a composition of BaZr0.8Gd0.2O3-α, BaZr0.8Ga0.2 O3-α or a composition represented by a general formula: BaZr1-xInxO3-α... and can be pumped by visible light
Data Source
AI summary
The optically pumped semiconductor according to the present invention is an optically pumped semiconductor that is a semiconductor of a perovskite oxide. The optically pumped semiconductor has a composition represented by a general formula: BaZr1-xMxO3-α, where M denotes at least one element selected from trivalent elements, x denotes a numerical value more than 0 but less than 0.8, and α denotes an amount of oxygen deficiency that is a numerical value more than 0 but less than 1.5. The optically pumped semiconductor has a crystal system of a cubic, tetragonal, or orthorhombic crystal. When lattice constants of the crystal system are referred to as a, b, and c, provided that a ≤ b ≤ c, conditions that 0.41727 nm ≤ a, b, c ≤ 0.42716 nm and a/c ≥ 0.98 are satisfied.