Coupling heterostructured CoP-NiCoP nanopin arrays with MXene (Ti3C2Tx) as an efficient bifunctional electrocatalyst for overall water splitting.

ABSTRACT

Developing a highly effective bifunctional electrocatalyst for alkaline-condition electrochemical water splitting is both essential and challenging. The work presented here successfully synthesizes and employs a heterostructured CoP-NiCoP ultra-long nanopin array in situ growing on MXene (Ti3C2Tx) as a stable bifunctional electrocatalyst for electrochemical water-splitting. The heterogeneous structure formed by CoP nanoparticles and NiCoP nanopins provides extra active sites for water-splitting. Also, Ti3C2Tx works as a support substrate during electrochemical operations, accelerating mass transfer, ion transport, and rapid gas product diffusion. Meanwhile, throughout the catalytic process, the dense nanopin arrays shield Ti3C2Tx from further oxidation. At a result, the CoP-NiCoP-Ti3C2Tx (denoted as CP-NCP-T) demonstrated excellent catalytic activity, with overpotentials of just 46 mV for hydrogen evolution at 10 mA cm-2 and 281 mV for oxygen evolution at 50 mA cm-2. Furthermore, in 1.0 M KOH solution, the outstanding bifunctional electrode (CP-NCP-T || CP-NCP-T) exhibits efficient electrochemical water splitting activity (1.54 V@10 mA cm-2) and outperforms the comparable device Pt/C || IrO2 (1.62 V@10 mA cm-2).