Ni₃ZnC_0.7 nanodots decorated nitrogen-doped carbon nanotube arrays as a self-standing bifunctional electrocatalyst for overall water splitting

Developing of inexpensive, high-efficient, and earth-abundant bifunctional catalysts for water splitting is of great significance for green and sustainable energy development. Herein, a bifunctional hybrid electrocatalyst of Ni₃ZnC_0.7 nanodots in-situ grown on nitrogen-doped carbon nanotube (Ni₃ZnC_0.7/NCNT) arrays is synthesized by a one-step template strategy with 1, 3, 5-triamino-2, 4, 6-trinitrobenzene serving as carbon/nitrogen sources, ZnO nanorods as template and zinc source, and nickel foam as substrate and nickel source. Benefiting from the introduction of Ni₃ZnC_0.7 nanodots and nitrogen doping to the carbon nanotubes, the Ni₃ZnC_0.7/NCNT-700 arrays exhibit superior hydrogen evolution reaction and oxygen evolution reaction catalytic activity in terms of low overpotential (203 mV and 380 mV vs RHE at 10 mA cm⁻² for hydrogen evolution reaction and oxygen evolution reaction, respectively). When the Ni₃ZnC_0.7/NCNT-700 is served as both anode and cathode catalysts for overall water splitting, a potential of 1.66 V is needed to deliver a current density of 10 mA cm⁻², and it also displays negligible degradation after 24 h of operation in alkaline solution. The present work not only provides an efficient bifunctional electrocatalyst for overall water splitting, but also offers a new strategy to design and synthetize the bimetallic carbide.