Surface Photovoltage Measurements on a Particle Tandem Photocatalyst for Overall Water Splitting

Author(s)

Melo, Jr., Mauricio A. ^{[1, 2]} ; Wu, Zongkai ^[2] ; Nail, Benjamin A. ^[2] ; De Denko, Alexandra T. ^[2] ; Nogueira, Ana F. ^[1] ; Osterloh, Frank E. ^[2]

Affiliation

^[1] Univ Estadual Campinas, UNICAMP, Inst Chem, POB 6154, BR-13084971 Campinas, SP - Brazil

^[2] Univ Calif Davis, Dept Chem, One Shields Ave, Davis, CA 95616 - USA

• Document type: Journal article
• Source: Nano Letters; v. 18, n. 2, p. 805-810, FEB 2018.
• Web of Science Citations: 23

Abstract

Surface photovoltage spectroscopy (SPS) is used to measure the photopotential across a Ru-STiO3:Rh/BiVO4 particle tandem overall water splitting photocatalyst. The tandem is Synthesized from Ru-modified SrTiO3:Rh nanocrystals and BiVO4 microcrystals by electrostatic assembly followed by thermal annealing. It splits water into H-2 and O-2 with an apparent quantum efficiency of 1.29% at 435 nm and a Solar to hydrogen conversion efficiency of 0.028%. According to SPS, a photovoltage develops above 2.20 eV, the effective band gap of the tandem, and reaches its maximal value of -2.45 V at 435 nm (2.44 mW cm(-2)), which corresponds to 96% of the theoretical limit of the photocatalyst film on the fluorine-doped tin-oxide-coated glass (FTO) substrate: Charge separation is 82% reversible with 18% of charge Carriers being trapped in defect states. The unusually strong light intensity dependence of the photovoltage (1.16 V per decade) is attributed to depletion layer changes inside of the BiVO4 microcrystals. These findings promote the understanding, of solar energy conversion with inorganic particle photocatalysts. (AU)

• FAPESP's process: 14/22388-3 - Optimizing photochemical charge separation at nanoscale interfaces as a way to improve the solar energy to fuel conversion efficiency of water splitting photocatalysts
• Grantee: Mauricio Alves de Melo Junior
• Support type: Scholarships abroad - Research Internship - Post-doctor