An hourglass-shaped nickel-based polyoxometalate crystalline material as a highly efficient bifunctional electrocatalyst for the oxygen evolution reaction and detection of H2O2

Abstract

The development of high-performance and low-cost catalysts toward the oxygen evolution reaction (OER) is critical for making them promising candidates to replace noble metal catalysts. Here, we report a novel hourglass-shaped {P₄Mo₆} crystalline material with Ni as the metal center (named CUST-576) and investigate its electrocatalytic oxygen evolution and H₂O₂ detection performance. In this work, composite electrodes containing Ni-{P₄Mo₆} crystals and carbon black (AB) were prepared by physically mixing crystals and used to run electrochemical tests. The composite has demonstrated relatively favorable OER properties compared to other known polyoxometalate (POM)-based materials. Specifically, the CUST-576&AB (1 : 2) composite exhibited the best catalytic activity toward the OER with a low overpotential of 320 mV at a current density of 10 mA cm⁻², and a small Tafel slope of 67 mV dec⁻¹. Furthermore, the composite showed better stability in alkaline electrolytes. Studies have shown that the actual active substances are in situ generated NiOOH, Ni(OH)₂, also confirming the pre-catalyst role of polyoxometalate under electrochemical OER conditions. Besides, this composite can be used to detect H₂O₂. In the future, this work will open up new avenues for designing POMs with new structures and POM-based catalysts in electrocatalytic applications.