Investigation of enhanced electro-catalytic HER/OER performances of copper tungsten oxide@reduced graphene oxide nanocomposites in alkaline and acidic media

Abstract

In this paper, we investigate the electro-catalytic hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of synthesized copper tungsten oxide@reduced graphene oxide (CuWO₄@rGO) nanocomposites. The prepared CuWO₄@rGO nanocomposites show bifunctional electro-chemical performances for the HER and OER via water splitting reactions in alkaline (0.5 M KOH) and acidic (0.5 M H₂SO₄) media. Cyclic voltammetry (CV) and linear sweep voltammetry (LSV) reveal superlative HER and OER performances of the CuWO₄@rGO nanocomposites. The onset over-potentials of the CuWO₄@rGO nanocomposites were found to be ∼270 and ∼330 mV for the OER in 0.5 M KOH and 0.5 M H₂SO₄, respectively, while the onset potentials were found to be ∼180 and ∼135 mV for the HER in 0.5 M KOH and 0.5 M H₂SO₄, respectively. The CuWO₄@rGO nanocomposites also showed lower Tafel slopes of ∼110 and ∼315 mV dec⁻¹ for the OER in 0.5 M KOH and 0.5 M H₂SO₄, respectively, while the Tafel slopes of the CuWO₄@rGO nanocomposites were found to be ∼192 and ∼212 mV dec⁻¹ for the HER in 0.5 M KOH and 0.5 M H₂SO₄, respectively. Hence, the small energy loss of low-cost electro-catalysts during electro-chemical water splitting reactions reveals comparable HER/OER performances with noble electro-catalysts.