Cr(III)-complex tethered lacunary polyoxometalate as an efficient electrocatalyst for hydrogen evolution reaction in aqueous media

Abstract

A lacunary polyoxometalate-based hybrid material, wherein Cr (acac)3 complex is covalently tethered through aminopropyltrimethoxysilyl groups to a Keggin-type lacunary phosphomolybdate anion, [PMo11O39]7-, is reported as a new heterogeneous electrocatalyst for the efficient electrocatalytic hydrogen evolution process. Physicochemical characterization techniques, like FT-IR spectroscopy, X-ray diffraction (XRD), and energy dispersive X-ray (EDX) analyses confirmed the successful functionalization and synthesis of desired material. The prepared hybrid material revealed eminent hydrogen evolution activity with a low overpotential of 330 mV to attain a 10 mA cm−2 current density and a Tafel slope of 150 mV.dec−1. Additionally, it also exhibited outstanding electrochemical stability in H2SO4 (0.5 M) over 8 h and catalytic activity retention even after 2000 catalytic cycles. This work introduces an appropriate procedure for preparing inexpensive and highly active electrocatalysts for replacing precious Pt counterparts in hydrogen evolution process.