Nitrogen doped carbon nanotube confined rare earth oxide-alloy heterostructure for efficient electrocatalytic water dissociation

It is crucial to design highly active, durable, and low precious metal mass-loaded hydrolysis ionization catalysts to promote slow water dissociation for hydrogen production. Herein, a series of armor-like catalyst heterogeneous structures of rare earth (RE) oxide/alloy confined within carbon nanotubes (RuCo/CeO 2 -NCNTs) was prepared using a one-step pyrolysis phase separation strategy. The prepared catalysts need only overpotentials of 12 and 51 mV for hydrogen evolution reaction (HER) and 141 and 192 mV for oxygen evolution reaction (OER) to achieve a current density of 10 mA/cm 2 in 1.0 mol/L KOH and 0.5 mol/L H 2 SO 4 electrolytes. Under alkaline conditions, both HER and OER can work steadily for 1000 h. The turnover frequency (TOF) values of HER and OER are 33.08 s –1 (@100 mV) and 12.75 s –1 (@300 mV) in alkaline environments, respectively. The in situ electrochemical impedance spectroscopy (EIS) test results further confirm that the introduction of cerium oxide optimizes the mass transfer process during the electrochemical process and enhances catalytic activity. The synergistic effect of the RuCo and CeO 2 heterostructure confined within NCNTs, combined with the increased conductivity resulting from the expansion of the conductive channels, accelerates reaction kinetics and enhances performance. This study also demonstrates the confinement of RE oxide heterostructures within NCNTs, providing a new solution for the development of novel RE-based catalysts and the high-value utilization of RE.