Abstract
Cost-effective and efficient electrocatalysts for hydrogen generation are appealing and highly required. Here, we present copper oxide-nickel oxide nanospheres (CuO-NiO@GP), copper oxide-cobalt oxide nanospheres (Cu2O-Co3O4@GP), CuO-NiO/carbon nitride nanocomposite (CuO-NiO/CN@GP) and Cu2O-Co3O4/carbon nitride nanocomposite (Cu2O-Co3O4/CN@GP) decorated graphite pencil as effective electrocatalysts for oxygen and hydrogen evolution reactions (OER, HER). CuO-NiO@GP, Cu2O-Co3O4@GP, CuO-NiO/CN@GP and Cu2O-Co3O4/CN@GP were used as working electrode and revealed tremendous OER and HER activity at low over-potentials in KOH and H2SO4 solutions. Among, CuO-NiO@GP, CuO-NiO/CN@GP, Cu2O-Co3O4@GP and Cu2O-Co3O4/CN@GP, the superior catalytic activity is displayed by CuO-NiO/CN@GP which gave current density of 20 mAcm(-2) at potential of 1.411 V (overpotential = 0.181 V) by using 1.0 M KOH concentration. CuO-NiO/CN@GP demonstrated higher catalytic performance toward OER as comparing to CuO-NiO@GP, Cu2O-Co3O4@GP and Cu2O-Co3O4/CN@GP. Similarly, CuO-NiO/CN@GP need the lowest potential of -0.762 and -0.858 V to obtain the current density of 10 mAcm(-2) and 20 mAcm(-2) in HER catalytic performance utilizing 0.5 M H2SO4 solution. Thus, it was observed from the LSVs of CuO-NiO@GP, CuO-NiO/CN@GP, Cu2O-Co3O4@GP and Cu2O-Co3O4/CN@GP that CuO-NiO/CN@GP shows greater catalytic activity and found more efficient and active in both OER and HER because CuO-NiO/CN@GP requires a low over potential, which produced 10 mAcm(-2) and 20 mAcm(-2) in both OER and HER. CuO-NiO/CN@GP demonstrates lower Tafel slopes of 171 mV dec(-1) and 129 mV dec(-1) in HER and OER, respectively. (C) 2021 Elsevier B.V. All rights reserved.