Synthesis of high-surface-area nanoporous BiVO4 electrodes
AssigneeWisconsin Alumni Research Foundation
InventorsKyoung-Shin Choi, Tae Woo Kim
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Abstract
Photoelectrochemical materials and photoelectrodes comprising the materials are provided. The photoelectrochemical materials comprise a porous, high-surface-area BiVO4 that is composed of particles smaller than the hole diffusion length of BiVO4.
Claims20
An electrode comprising a porous network of connected BiVO4 particles, including BiVO4 particles that are merged at their interfaces, wherein the porous network has a surface area of at least about 20 m2/g, as measured by the Brunauer-Emmett-Teller method, and further wherein the electrode is characterized in that it generates a photocurrent density of at least 0.2 mA/cm2 at 1 V versus reversible hydrogen electrode for water oxidation under 100 mW/cm2, AM 1.5 G illumination.
An electrode comprising:
- a porous network of connected BiVO4 particles, including BiVO4 particles that are merged at their interfaces, wherein the porous network has a surface area of at least about 10 m2/g, as measured by the Brunauer-Emmett-Teller method;
- and a coating of oxygen evolution catalyst on the surfaces of the BiVO4 particles,
- wherein the coating of oxygen evolution catalyst comprises an inner layer of a first oxygen evolution catalyst in direct contact with the surfaces of the BiVO4 particles and an outer layer of a second oxygen evolution catalyst disposed on the inner layer, wherein the first oxygen evolution catalyst is characterized in that it creates fewer interfacial states that can serve as recombination centers at the BiVO4/oxygen evolution catalyst interface than would the second oxygen evolution catalyst and the second oxygen evolution catalyst is characterized in that it has higher catalytic activity for oxygen evolution than does the first oxygen evolution catalyst.
An electrode comprising BiVO4 particles and a coating of oxygen evolution catalyst on the surfaces of the BiVO4 particles, wherein the coating of oxygen evolution catalyst comprises an inner layer of a first oxygen evolution catalyst in direct contact with the surfaces of the BiVO4 particles and an outer layer of a second oxygen evolution catalyst disposed on the inner layer, wherein the first oxygen evolution catalyst is characterized in that it creates fewer interfacial states that can serve as recombination centers at the BiVO4/oxygen evolution catalyst interface than would the second oxygen evolution catalyst and the second oxygen evolution catalyst is characterized in that it has higher catalytic activity for oxygen evolution than does the first oxygen evolution catalyst.
A photoelectrochemical cell comprising:
- a working electrode comprising a porous network of connected BiVO4 particles, including BiVO4 particles that are merged at their interfaces, wherein the porous network has a surface area of at least about 20 m2/g, as measured by the Brunauer-Emmett-Teller method, and further wherein the working electrode is characterized in that it generates a photocurrent density of at least 0.2 mA/cm2 at 1 V versus reversible hydrogen electrode for water oxidation under 100 mW/cm2, AM 1.5 G illumination;
- a counter electrode in electrical communication with the working electrode;
- and
- an electrolyte solution in which the working electrode and the counter electrode are immersed.
A method for electrochemical reactions using a photoelectrochemical cell comprising:
- a working electrode comprising a porous network of connected BiVO4 particles, including BiVO4 particles that are merged at their interfaces, wherein the porous network has a surface area of at least about 20 m2/g, as measured by the Brunauer-Emmett-Teller method, and further wherein the working electrode is characterized in that it generates a photocurrent density of at least 0.2 mA/cm2 at 1 V versus reversible hydrogen electrode for water oxidation under 100 mW/cm2, AM 1.5 G illumination;
- a counter electrode in electrical communication with the working electrode;
- and an electrolyte solution in which the working electrode and the counter electrode are immersed, the method comprising:
- exposing the BiVO4 electrode to radiation having energy greater than the bandgap of the BiVO4, such that:
- the BiVO4 particles absorb the radiation to produce electron-hole pairs;
- the holes are transported to the electrolyte-BiVO4 interface where they undergo oxidation reactions with the electrolyte;
- and the electrons are transported to the counter electrode where they undergo reduction reactions with the electrolyte.
A method of making an electrode, the method comprising:
- applying an organic solution comprising vanadium-containing precursor molecules to the surface of an electrode comprised of plate-like BiOX crystals, where X represents a halogen atom or a mixture of halogen atoms;
- and
- heating the organic solution-covered electrode comprised of plate-like BiOX crystals to form an electrode comprising a porous network of connected BiVO4 particles, including BiVO4particles that are merged at their interfaces;
- wherein the porous network of connected BiVO4 particles has a surface area of at least about 20 m2/g, as measured by the Brunauer-Emmett-Teller method, and further wherein the electrode is characterized in that it generates a photocurrent density of at least 0.2 mA/cm2 at 1 V versus reversible hydrogen electrode for water oxidation under 100 mW/cm2, AM 1.5 G illumination.
Dependencies are inferred from the claim text.