“Carbohydrate-Universal” electrolyzer for energy-saving hydrogen production with Co3FePx@NF as bifunctional electrocatalysts

Abstract

Hydrogen production via solar-powered water electrolysis allows abundant but intermittent energy to be directly converted into clean fuel in a sustainable manner. However, this method is hindered by the sluggish O2 evolution reaction (OER). The carbohydrate oxidation reaction (COR) can potentially replace the OER for effective H2 production with low-energy consumption due to its more favourable thermodynamics. Herein, Co3FePx@NF is used as a “carbohydrate-universal” catalyst for four representative COR that had a potential of 1.24 V vs RHE (to 10 mA cm−2) which was 20% (310 mV) lower than commercial electrocatalysts for OER. In addition, the presence of carbohydrates had no negative effect on the high performance of Co3FePx@NF for hydrogen evolution at cathode. Motivated by the above performance improvements, a novel electrolyzer was developed that integrates H2 production and COR using Co3FePx@NF as a bifunctional electrocatalyst. A cell voltage of only 1.35 V was required to achieve a current density of 10 mA cm−2, which was much lower than commercial water splitting systems (nomarlly 1.8∼2.0 V), highlighting that the electrolyzer in this paper has great potential for use in energy-saving H2 production. Due to the improved design, the electrolyzer can be easily driven by a single perovskite solar cell delivering a solar-to-hydrogen efficiency of 13.3%, which provides a convenient and efficient way to achieve overall-sustainable H2 production. This work may serve as the foundation for further energy-saving hydrogen production technologies and carbohydrate-containing waste treatment by the rational design of electrolyzers.