Coupling furfural oxidation for bias-free hydrogen production using crystalline silicon photoelectrodes.

Ko, Myohwa; Lee, Myounghyun; Kim, Taehyeon; Jin, Wonjoo; Jang, Wonsik; Hwang, Seon Woo; Kim, Haneul; Kwak, Ja Hun et al. · Nat Commun · 2025

basic_science · Level V

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Abstract

To commercialize the technology of photoelectrochemical hydrogen production, it is essential to surpass the US. Department of Energy target of 0.36 mmol h<sup>-1</sup> cm<sup>-2</sup> for 1-sun hydrogen production rate. In this study, we utilize crystalline silicon, which can exhibit the highest photocurrent density (43.37 mA cm<sup>-2</sup>), as the photoelectrode material. However, achieving bias-free water splitting (>1.6 V) remains challenging due to the intrinsic low photovoltage of crystalline silicon (0.6 V). To address this limitation, we replace water oxidation with low-potential furfural oxidation, enabling not only bias-free hydrogen production but also dual hydrogen production at both the cathodic and anodic sides. This approach results in a record 1-sun hydrogen production rate of 1.40 mmol h<sup>-1</sup> cm<sup>-2</sup>, exceeding the Department of Energy target by more than fourfold.