Earth-Abundant-Based Photocatalysts for Efficient and Selective H<sub>2</sub> Production through Reforming of Formic Acid under Visible Light
Houeida Issa Hamoud, Łukasz Wolski, Hanen Abdelli, R. Chtourou, Oleg I. Lebedev, C. Martin, Dong Fan, Guillaume Maurin, A. Maignan, Mohamad El-Roz
Abstract
Hydrogen is considered one of the most promising future solar fuels. Nowadays, particular attention is directed to H 2 production through the photoreforming of formic acid (FAc). However, acceptable conversion of FAc into H 2 is usually observed only at relatively high temperatures or in the presence of expensive noble metal catalysts. In this study, Cu 2 O was combined with selected semiconducting metal oxide, namely, CuO, CeO 2, Fe 2 O 3, Cu–Fe–O spinel, Nb 2 O 5, TiO 2, and Fe 3 O 4, and applied for FAc dehydrogenation at room temperature under visible irradiation. It was found that the type of semiconductor has a significant impact both on the activity and reaction selectivity of the Cu 2 O-based catalysts. A synergetic activity with the highest FAc conversion (9.89 mmol·g –1 ·h –1 ) and selectivity to H 2 (>99%) was observed for the Earth-abundant Cu 2 O/Fe 3 O 4 composite. This synergetic enhancement, with respect to monocomponent ones, originates from an efficient separation of the photogenerated charge carrier according to Z-scheme mechanism accompanied by an in situ restructuring of Cu 2 O into Cu 0 /Cu 2 O. In addition, as-formed Cu 0 particles, resulting from the restructuring, are found to be an active component responsible for highly efficient H 2 production over Cu 2 O/Fe 3 O 4 . The density functional theory calculations confirm this hypothesis and highlight the role of Cu 0 in the reaction mechanism.