Tailored Cobalt Single Atoms on Strong Metal–Support Interactions Drive the Tandem Bifunctional Electrocatalytic Overall Water Splitting

The rational strategy for synthesizing highly stable single-atom catalysts (SAC) remains very challenging. However, SAC aggregation and migration can be tackled through strong metal–support interaction (SMSI). Herein, we disclose the cobalt single-atom decoration over the MoP 2 /WP 2 support (Co 1 –MoP 2 /WP 2 ) utilizing a facile sonication followed by calcination strategy, confirmed by HAADF-STEM, XANES, and EXAFS. Subsequently, Co 1 –MoP 2 /WP 2 loaded in nickel foam demands a low overpotential of 49 mV for the hydrogen evolution reaction (HER) and 250 mV for the oxygen evolution reaction (OER) at a current density of 10 mA cm –2 . An alkaline water electrolyzer designed using the Co 1 –MoP 2 /WP 2 catalyst as both the anode and cathode delivers a very low cell voltage of 1.49 V at 10 mA cm –2, surpassing the benchmark electrocatalyst with a stability of 48 h. Importantly, X-ray absorption spectroscopy discloses the local atomic and electronic charge transfer between Co SAC and the SMSI support, leading to a decrease in the overpotential and an increase in its catalytic efficiency. Furthermore, DFT is used to assess the change in the electronic characteristics caused by anchoring Co SAC on MoP 2 /WP 2, resulting in improved electrocatalytic properties. Thus, this work provides a key insight into enhancing the overall water splitting performance by incorporating SAC into the MoP 2 /WP 2 support.