Constructing robust NiFe LDHs-NiFe alloy gradient hybrid bifunctional catalyst for overall water splitting: one-step electrodeposition and surface reconstruction

NiFe layered double hydroxides (NiFe LDHs) have been intensively developed for the oxygen evolution reaction (OER) in alkaline media; however, their unsatisfactory hydrogen evolution reaction (HER) performance limits their practical application in overall water splitting. Herein, a simple and efficient one-step electrodeposition method is used to accomplish in situ growth of NiFe LDHsNiFe alloy gradient hybrid coatings on a carbon cloth (CC). Within the binder-free electrode, NiFe LDHs nanosheets with a low-crystalline nature exhibit highly active bifunctional OER/HER activities, and the NiFe alloy acts as a stable electron highway and strong skeleton bridge between NiFe LDHs and the CC. When the electrodes are simultaneously employed as the cathode and anode for overall water splitting, they require low cell potentials of 1.441 V at 10 mA-cm(-2) and 1.703 V at 100 mA-cm(-2), respectively, and they demonstrate outstanding stability at a current density greater than 100 mA-cm-2 for more than 100 h. This is one of the best bifunctional OER and HER catalysts for overall water splitting. Both lattice defects and surface reconstructions crucially contribute to the bifunctional OER/ HER activities of NiFe LDHs. This simple and scalable synthesis approach presents an intriguing paradigm for industrial production, and the fabricated electrode has potential application in high-current-density water splitting.