An efficient bias-free Si photocathode coupled BiVO${}_4$-triethanolamine photoelectrochemical fuel cell for simultaneous pollutant treatment and hydrogen production

Photoelectrochemical (PEC) fuel cells that enable organic pollutants degradation while generating H${}_2$ are regarded as a viable approach in addressing global energy and environmental issues. Herein, an efficient PEC fuel cell is constructed using oxygen vacancy-rich BiVO${}_4$ (O${}_V$:BiVO${}_4$) as the photoanode and triethanolamine (TEOA) pollutant as the fuel. Under AM 1.5 G, this O${}_V$:BiVO${}_4$-TEOA PEC fuel cell shows an ultra-high photo-driven current density of 20.40 mA cm${}^{-2}$ at 1.23 V versus reversible hydrogen electrode, which is superior to most reported PEC fuel cells. The Faradic efficiency of H${}_2$ production is about 97.26%, and no CO${}_2$ is released in the anode chamber due to the strong CO${}_2$ adsorption by excess TEOA. Further integration of a Pt/C cocatalyst coated Si photocathode in the O${}_V$:BiVO${}_4$-TEOA PEC fuel cell can achieve bias-free H${}_2$ production with a current density of 10.17 mA cm${}^{-2}$. The experimental and theoretical calculation results reveal the importance of the robust complexation between the O${}_V$:BiVO${}_4$ photoanode and TEOA, which ensures thorough conversion of chemical energy in TEOA and high activity of the PEC fuel cell. This work will guide the design of efficient PEC fuel cells for simultaneous pollutant treatment and H${}_2$ production. (© 2023 Wiley‐VCH GmbH)