Triggering Redox Active Sites Through Electronic Structure Modulation in rGO Encapsulated Mixed Transition Metal...

Designing and developing noble-metal-free catalysts are of current interest in clean hydrogen generation via water splitting. As carbonaceous species are ideal choices as templates for various electrocatalysis, an improved synthetic route and an in-depth understanding of their electrochemical performance are essential. Herein, we have investigated the catalytic performance of rGO-encapsulated Mn and V mixed oxide hybrid structures (MVG) on a NiFeP matrix, focusing on their potential for catalyzing hydrogen evolution in an alkaline environment. The hierarchical MVG hollow microspheres hybrids are synthesized via a simple one-step in situ solvothermal method and MVG/NiFeP coatings are developed by facile electroless plating technique. As evidenced from the X-ray photoelectron spectroscopy, the multiple redox active sites in the 3d-band of Mn and V in MVG hybrid structural coatings serve as electron pumps, and rGO facilitates electronic conductions during catalytic reactions. The modulated electronic structure and strong synergistic effects between NiFeP and MVG facilitate rapid electron transfer kinetics, and the hybrids demonstrate superior HER performance. Consequently, the structural hybrid coatings possess an enhanced electronic conducting path (lower R_CT = 545.3 Ω) and large ECSA values with a lower overpotential of 85 mV at 10 mA cm^-2 and a reduced Tafel slope of 64.1 mV dec^-1 with Volmer-Heyrovsky mechanism in alkaline media.