Realizing efficient electrochemical overall water electrolysis through hierarchical CoP@NiCo-LDH nanohybrids

Abstract

It is very important to design the catalysts with special spatial architectures and excellent electrochemical performance. It is well known that non-noble metal catalysts are inferior to Pt-like ones in electro-activity. However, their catalytic ability can be improved by the synergistic effect of different components. Herein, we synthesize several dendritic-like CoP@NiCo-LDH hetero-catalysts by a multi-step growth route. The CoP@NiCo LDH-100 samples present an overpotential of 225 mV @ 46.6 mV dec−1 for OER and 68.7 mV @ 74.03 mV dec−1 for HER, which is superior to the commercial IrO2 (OER) and Pt/C (HER) in alkaline electrolyte. The density functional theory (DFT) calculation demonstrates that the composites possess low adsorption energy (1.11 eV) and tunable charge redistribution at the interface. An increased Fermi-level PDOS value proves the enhanced conductivity of the catalyst. The upward shift of the D-band center optimizes the desorption of the intermediates and accelerates the hydrolysis dissociation process. This increases the HER activity and thus reduces the overall electrolysis voltage.