Colloidal synthesis of hexagonal CuFe(S x Se 1− x ) 2 nanoplates with exposed highly active (220) facets for boosting overall water splitting

Heteroatom doping and crystal facet engineering are well-established strategies for enhancing the intrinsic activity of catalysts by modulating their chemical compositions, electronic structures, surface properties and so on. Herein, we report the synthesis of uniform and monodisperse CuFe(S x Se 1− x ) 2 nanoplates with a controlled S/Se ratio via a facile hot-injection method. The resulting CuFe(S x Se 1− x ) 2 nanoplates show high exposure of active (220) facets, which can provide more active sites and optimize the surface activity of the nanoplates, thereby promoting both mass and electron transport. Additionally, density functional theory calculations suggest that the incorporation of Se atoms can not only reduce the band gap but also efficiently regulate the d-band center of Fe atoms, leading to a balanced adsorption and desorption capacity of H* intermediates. Benefiting from the above advantages, the titled catalyst displays excellent electrocatalytic activities toward electrochemical water splitting. Particularly, optimal CuFe(S 0.8 Se 0.2 ) 2 shows low overpotentials of 113 mV and 271 mV at 10 mA cm −2 to drive the hydrogen and oxygen evolution reactions in 1.0 M KOH, respectively. When used as both the cathode and anode for overall water splitting, a low voltage of 1.61 V was achieved, along with excellent stability for at least 18 h. This work may provide insights into the synthesis of multinary chalcogenides with high-entropy as efficient catalysts for renewable energy applications.