Heterogeneous interface engineering of CoPSe and FePSe3 on open frameworks for boosting highly efficient overall water splitting

Abstract

Enhancing intrinsic activity of nanostructured heterogeneous catalysts is an effective strategy for improving electrocatalytic performance for hydrogen/oxygen evolution reactions (HER/OER), but it remains challenging. Here, phosphorus (P) and selenium (Se) atoms are incorporated into an open Co-Fe-based Prussian blue analogues to form a heterostructure consisting of CoPSe and FePSe3 via a one-step pyrolysis strategy. The CoPSe/FePSe3 heterojunction greatly reduces the overpotential for HER (91 mV) or OER (172 mV), which is close to that of Pt/C or much better than that of RuO2, respectively. Co-doping of P and Se non-metallic atoms promotes the reaction kinetics and the exposure of active sites in the framework structure with a large specific surface area. The interactions between CoPSe and FePSe3 can eagerly promote the interfacial electron transfer to enhance HER/OER activities. The carbon skeleton can effectively avoid the fast corrosion/aggregation of the embedded CoPSe/FePSe3 heterojunctions, thereby enhancing the catalytic/structural stability for HER/OER. Importantly, for overall water splitting, the electrolyzer with CoPSe/FePSe3 catalyst only requires an overpotential of 0.35 V to achieve a long-term stability (36 h) at 10 mA cm−2, with Faradaic efficiencies near 100 %. This work sheds a new light on promotion of intrinsic activity of heterostructured catalysts for water splitting.