Methods and apparatus for ultrathin catalyst layer for photoelectrode

Patent metadata

Field	Value
Publication number	US-9920438-B2
Application number	US-201213544940-A
Country	US
Kind code	B2
Filing date	Jul 9, 2012
Priority date	Jul 7, 2011
Publication date	Mar 20, 2018
Grant date	Mar 20, 2018

Abstract

In exemplary implementations of this invention, a photoelectrode includes a semiconductor for photocarrier generation, and a catalyst layer for altering the reaction rate in an adjacent electrolyte. The catalyst layer covers part of the semiconductor. The thickness of the catalyst layer is less than 60% of its minority carrier diffusion distance. If the photoelectrode is a photoanode, it has an OEP that is more than the potential of the valance band edge but less than the potential of the Fermi level of the semiconductor. If it is a photocathode, it has an RHE potential that is less than the potential of the conduction band edge but more than the potential of the Fermi level of the semiconductor. The absolute value of difference (OEP minus potential of valence band edge, or RHE potential minus potential of conduction band edge) is greater than zero and less than or equal to 0.2V.

First claim

What is claimed is:

1. A photoanode that includes:
(a) a semiconductor for photocarrier generation; and
(b) a catalyst layer for altering the rate of an electrochemical reaction in an electrolyte adjacent to the catalyst layer;

wherein
(i) the semiconductor primarily comprises a first material and the catalyst layer primarily comprises a second material, the first material being different than the second material,
(ii) the catalyst layer covers a portion of the semiconductor's surface,
(iii) the thickness of the catalyst layer is less than 60% of the minority carrier diffusion distance of the catalyst layer,
(iv) the photoanode is adapted to have an OEP that is more than the potential of the valance band edge of the semiconductor and less than the potential of the Fermi level of the semiconductor, the absolute value of the difference between the OEP and the potential of the valence band edge being greater than zero and less than or equal to 0.2V, and
(v) the interior of the semiconductor is doped with a first n-type dopant at a first dopant concentration, and an exterior region of the semiconductor that is not covered by the catalyst layer is doped with a second n-type dopant at a second dopant concentration, the second dopant concentration being greater than the first dopant concentration.

2. The photoanode of claim 1 , wherein the first n-type dopant and second n-type dopant both comprise phosphorous.

3. A photoelectrochemical cell, wherein:
(a) the photoectrochemical cell includes a photoanode;
(b) the photoanode includes a semiconductor for photocarrier generation and a catalyst layer for altering the rate of an electrochemical reaction in an electrolyte adjacent to the catalyst layer;
(c) the semiconductor primarily comprises a first material and the catalyst layer primarily comprises a second material, the first material being different than the second material;
(d) the catalyst layer covers a portion of the semiconductor's surface;
(e) the thickness of the catalyst layer is less than 60% of the minority carrier diffusion distance of the catalyst layer;
(f) the photoanode is adapted to have an OEP that is more than the potential of the valance band edge of the semiconductor and less than the potential of the Fermi level of the semiconductor, the absolute value of the difference between the OEP and the potential of the valence band edge being greater than zero and less than or equal to 0.2V; and
(g) the interior of the semiconductor is doped with an n-type dopant, and an exterior region of the semiconductor that is not covered by the catalyst layer is doped with an n+dopant.

Assignees

• Jun Kimin
• Jacobson Joseph
• Massachusetts Inst Technology

Inventors

• Jun Kimin
• Jacobson Joseph

Classifications

• C25B11/02

  characterised by shape or form · CPC title

• C25B11/0452

  Chemistry & Metallurgy · mapped topic

• Y02E10/542

  Dye sensitized solar cells · CPC title

• H01G9/2036

  comprising mixed oxides, e.g. ZnO covered TiO2 particles · CPC title

• C25B1/003 Primary

  Chemistry & Metallurgy · mapped topic