NiSe Nanoparticles\nEmbedded Bimetallic MoCo Nanoflakes\nas an Effective Bifunctional Electrocatalyst for Water Splitting

Non-noble metals have shown superior\ncatalytic properties\ncompared\nto noble metal catalysts in green energy generation due to their cost-effectiveness\nand abundant availability. In our study, we introduced a novel heterostructure\ncomprising bimetallic MoCo nanoflakes as the substrate with anchored\nNiSe nanoparticles using a hydrothermal method. Various compositions\nof the MoCo–NiSe heterostructure were synthesized with different\nweight ratios of bimetallic MoCo and NiSe (2:1, 4:1, and 8:1) to determine\nthe optimal configuration for maximum efficiency. These composite\nmaterials were evaluated as bifunctional electrocatalysts in an alkaline\nmedium for the overall water splitting (HER/OER). Remarkably, the\namalgamation of bimetallic MoCo with NiSe exhibited enhanced electrochemical\nwater splitting due to increased surface area, porosity, and reduced\ncharge-transfer resistance. The MoCo–NiSe (8:1) electrocatalyst\ndemonstrated a significantly low overpotential of 277 mV (@ j = 10\nmA cm<sup>–2</sup>) and the lowest Tafel slope of 139 mV dec<sup>–1</sup> for OER. Similarly, MoCo–NiSe (2:1) showed\ncomparable kinetics for HER with lower overpotential (245 mV @ 10\nmA cm<sup>–2</sup>) and Tafel values (50 mV dec<sup>–1</sup>). Furthermore, the electrocatalysts showed excellent stability,\nas evidenced by chronoamperometry studies conducted for 24 h for both\nthe OER and HER, with an efficiency exceeding 90%. Additionally, the\noverall water splitting (OWS) initiated at a lower onset potential\nof 1.66 V @ 10 mA cm<sup>–2</sup>, indicating the efficiency\nand stability achieved during electrocatalysis. The observed properties\nof the materials can be attributed to the synergistic effects between\nMoCo nanoflakes and well-dispersed NiSe nanoparticles within the nanoflakes.\nThis study presents a promising approach to creating novel nanomaterials\nfor energy conversion applications.