Highly electroactive Ni pyrophosphate/Pt catalyst towards hydrogen evolution reaction.

Robust electrocatalysts towards the resourceful and sustainable generation of hydrogen by splitting of water via electrocatalytic hydrogen evolution reaction (HER) is a prerequisite to realize high-efficient energy research. High electroactive catalysts for hydrogen production with ultra-low loading of platinum (Pt) have been under exhaustive exploration to make the cutting edge and cost-effectively reasonable for water splitting. Herein, we reports the synthesis of hierarchically structured nickel pyrophosphate (β-Ni2P2O7) by precipitation method and nickel phosphate (Ni3(PO4)2) by two different synthetic routes viz., simple, cost-effective precipitation and solution combustion process. Thereafter, Pt decorated nickel pyro- and phosphates (β-Ni2P2O7/Pt and Ni3(PO4)2/Pt) were prepared by using potassium hexachloroplatinate and ascorbic acid. The fabricated novel nickel pyro- and phosphate/Pt materials were utilized as a potential and affordable electrocatalysts for HER by water splitting. The detailed electrochemical studies exposed that the β-Ni2P2O7/Pt(1 μg cm-2 of Pt) electrocatalyst revealed as an excellent electrocatalytic performances for HER in acidic solution with an overpotential of 28 mV at -10 mA cm2, a Tafel slope of 32 mV/dec, and an exchange current density (j0) of -1.31 mA cm-2, which were close to the values obtained using eight times higher Pt amount as at Vulcan/Pt(8.0 μg cm-2 of Pt), commercial benchmarking electrocatalyst. Furthermore, β-Ni2P2O7/Pt electrocatalyst maintains an excellent stability for over -0.1 V vs RHE during 12 days, keeping j0 equal after the stability test (-1.28 mA cm-2). A very well distributed Pt NPs inside of the 'cages' on β-Ni2P2O7 structure with a crystalline pattern of 0.67 nm in distance to the Ni2P2O7/Pt electrocatalyst, helping the Volmer-Tafel mechanism with Tafel reaction as a major rate limiting step, acts to liberate very fast the Pt sites, after HER. The high electrocatalytic performance and remarkable durability expressed the β-Ni2P2O7/Pt material to be promising cost-effective electrocatalyst for hydrogen production.