Enhancing activity in a nanostructured BiVO4 photoanode with a coating of microporous Al2O3

Applied Catalysis B: Environmental Volume 200, January 2017, Pages 133–140

(A,B) FE-SEM images of “one-step” BiVO4 films obtained with 10 L cm−2 “paint” dropped and annealed on FTO at 400 ◦C. (C) FE-SEM image of a BiVO4/2Al2O3 film deposit. (D,E) Cross-sectional FE-SEM images for BiVO4 and BiVO4/2Al2O3, respectively.

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Writers: Murilo F. Gromboni and Dyovani Coelho and Lucia H. Mascaro and Adam Pockett and Frank Marken

Keywords: Water splitting; Solar energy; Photocatalysis; Ceramic coating; Photo-kinetics; Microporous membrane

Abstract: Nanostructured semiconductor photoanodes play an important role in solar fuel generation, and the design of the semiconductor − aqueous electrolyte interface can be crucial in enhancing the energy conversion efficiency. We have investigated the effects on photoelectrochemical oxygen evolution for monoclinic nanostructured BiVO4 films uncoated and coated with microporous sol-gel Al2O3 “over-layers”. Variation of the thickness of the Al2O3 coating (formed by surface sol-gel deposition and annealing at 435 °C) led to a reduction of pseudo-capacitance and allowed optimization of the quantum efficiency. Exploration of the photocurrent enhancement as a function of applied potential reveals two distinct potential domains/mechanisms: (i) a low bias region enhancement effect (assigned to a lowering of the rate of external recombination of electrons with oxygen) and (ii) a high bias region of enhancement (assigned to higher charge carrier mobility due to less trapping in surface states).

Daniela Caceta
Sobre Daniela Caceta 33 Artigos
Atua no Centro de Desenvolvimento de Materiais Funcionais.