Homogeneous Molecular Iron Catalysts for Direct Photocatalytic Conversion of Formic Acid to Syngas (CO+H 2 )

Hydrogen Production from Formic Acid by In Situ Generated Ni/CdS Photocatalytic System under Visible Light Irradiation

Simple and practical noble-metal-free catalyzed hydrogen production from sustainable resources, such as renewable formic acid, is highly desirable. Herein, the development of an efficient photocatalytic hydrogen production from aqueous solution of formic acid using in situ generated Ni/CdS photocatalytic system was described. CdS-Cys (Cys=l-cysteine) quantum dots (QDs) acting as photocatalyst with Ni(OAc)₂ as H₂ production catalyst precursor, a 94 % yield was obtained within 5 h under visible light irradiation at 50 °C. The average rate of H₂ production reached up to 282 μmol mg^-1  h^-1 with 99.8 % H₂ selectivity. Mechanistic studies indicate cooperation of dynamic quenching and static quenching of CdS-Cys QDs by Ni(OAc)₂ . Especially, Ni⁰ , generated in the dynamic quenching, accelerated the electron transfer by acting as an electron outlet and enhancing the stability of CdS to slow down the photocorrosion distinctly, delivering efficient H₂ production with high selectivity. Our study will inspire exploration of various efficient non-noble-metal catalysts for practical H₂ production from bio-based formic acid.