Unleashing the potential of NiO@V₂CT_x MXene-derived electrocatalyst for hydrogen and oxygen evolution

Harnessing the power of sustainable hydrogen energy requires the development of efficient, non-precious metal electrocatalysts for water splitting. 2D materials, particularly MXenes offer potential solutions, given their unique attributes like metal-like conductivity, hydrophilic surfaces, and rich chemistry. In this research, we synthesized NiO@V2CTx, a novel bifunctional electrocatalyst with a synergistic three-layer structure. This composite merge the tunable properties of V2CTx MXene with the catalytic capability of NiO nanoparticles. By varying the NiO concentrations, we synthesized four distinct composites, each showing unique electrochemical characteristics. The 7.5 % composite (VN3), in particular, exhibited superior electrochemical performance with overpotentials of 253 mV (HER) and 346 mV (OER), along with Tafel slopes of 104 mV/dec and 91 mV/dec, respectively, to reach a benchmark current density of 10 mAcm 2. However, higher concentrations lead to blockage of active sites that diminish performance. The low charge transfer resistance (11.33 omega) of the Niadsorbed V2CTx MXene contributes to the rapid reaction kinetics and enhanced performance. The composite displayed exceptional durability, indicating its potential for long-term application. It maintained a high current retention of 93 %, indicating outstanding electrochemical stability. Moreover, the cell configuration using NiO@V2CTx//NiO@V2CTx requires a cell voltage of 1.75 V for overall water splitting. In essence, the VN3 composition was found to be the "sweet spot" for achieving optimal electrochemical performance, potentially offering benefits like high catalytic activity, enhanced conductivity, and improved durability.