Graft-growth of CoCo-PBA on defect-rich Cu1.94S arrays for high-current-density water splitting

The renewable energy of hydrogen arouses efficient high-current-density electrocatalysts for sustainable and practical uses in water-splitting processes. Herein, bifunctional electrocatalysts of CoCo-PBA@Cu1.94S composite arrays on copper foam were successfully synthesized by an aqueous circulating ion-exchange strategy. The defect-rich Cu1.94S nanorod array (NRA) was initially formed as an in-situ template to engineer the graft growth of CoCo-PBA particles through the incorporation of Co ions in the intrinsic Cu vacancy sites. The matching crystal lattice of the two components enables the formation of CoCo-PBA@Cu1.94S heterostructures. The thickness of the CoCo-PBA layer could be regulated by changing the concentration of the cobalt solution. The synergistic contribution of CoCo PBA and Cu1.94S made the composite arrays behave excellent OER, HER, and overall water splitting activities in alkaline circumstances, in comparison to the similar architecture of CoCo-PBA@Cu(OH)2 nanowire array (NWA). The CoCo-PBA@Cu1.94S NRAs preserved low overpotentials of 372 and 379 mV vs. RHE towards OER and HER, along with good stability within 70 h and 120 h at a high current density of 500 mA cm–2. The sustainability performance for overall water splitting was steadily extended to 60 h at the current densities of 100 and 500 mA cm–2 through the chronopotentiometry strategy, the cell voltages remained over 99% and 95% of the initial value during the measurement, suggesting prominent durability of the composite electrode. The CoCo-PBA@Cu1.94S NRAs could be utilized as promising high-current-density bifunctional catalysts for industrial water electrolysis applications.