A rare polyoxometalate cluster [NiW12O44]14− based solid as a pre-catalyst for efficient and long-term oxygen evolution

Abstract

Polyoxometalates (POMs) are an eminent class of metal oxide anionic clusters of early transition metals with huge structural diversity. Herein, a [NiW₁₂O₄₄]¹⁴⁻ cluster based solid, (C₅H₇N₂)₆[NiW₁₂O₄₄], has been reported (PS-78). The [NiW₁₂O₄₄]¹⁴⁻ cluster bridges the missing gap of 1 : 12 hetero-POMs of Keggin and Silverton together with a coordination number of 8 of the central heteroatom (Ni). Furthermore PS-78 has been explored as an efficient and highly sustained oxygen evolution pre-catalyst in alkaline medium with an overpotential of 347 mV to attain a current density of 10 mA cm⁻² and long-term stability up to 96 hours. Furthermore, mechanistic investigation showed that in situ generated NiO and WO_x (x = 1, 2) species act as active species for the oxygen evolution reaction. This study will open up new avenues for exploring POMs' new topologies and the potential of POMs as effective pre-catalysts in electrocatalytic applications.