Graphene-Coated Copper Nanowire Networks as a Highly Stable Transparent Electrode in Harsh Environments Toward Efficiently Electrocatalytic Hydrogen Evolution Reaction
Copper nanowire networks (NWs) coated by a graphene layer through a carbon-enclosed chemical vapor deposition technique at a low temperature of 400 °C with a low sheet resistance of 23.2 Ω/sq and a high transmittance of 83.4 %, which is comparable to typical values of tin-doped indium oxide (ITO), as a transparent conducting electrode were demonstrated. The graphene-coated copper NWs networks with the low sheet resistance of less than 25 Ω/sq remain at an annealing temperature of 240 oC in a pure oxygen ambient for 1 hr while the sheet resistance less than 100 Ω/sq can be still maintained in natural sea water, acidic and basic solutions, respectively. The highly stable feature in harsh environments makes the graphene-coated copper nanowire networks suitable as a catalyst toward high-efficiency hydrogen evolution reactions (HER) in a low overpotential of 252 mV at 10 mA/Cm2 with a low Tafel slope of 67 mV/dec. The non-corrosive and anti-oxidant graphene-coated copper nanowire networks could be used as an alternative transparent conducting electrode in harsh environments, such as tandem photocatalytic water splitting.