The synergistic effect of light irradiation and interface engineering of the Co(OH)2/MoS2 heterostructure to realize the efficient alkaline hydrogen evolution reaction

Abstract

Photo-electrochemical and electrochemical water splitting are considered as effective ways to realize the efficient hydrogen evolution reaction and solve the increased energy demand. Herein, the photo-responsive MoS2 electrocatalyst modified with Co(OH)2 was synthesized on a carbon cloth (CC) by a facile approach. Benefiting from the heterogeneous interface between MoS2 and Co(OH)2, this hybrid catalyst shows superior HER activity in 1 M KOH aqueous solution with an overpotential of 117 mV at 10 mA cm−2 and a Tafel slope of 59.82 mV dec−1, which are smaller than those of MoS2/CC (an overpotential of 171 mV at 10 mA cm−2 and a Tafel slope of 90.78 mV dec−1) or Co(OH)2/CC (an overpotential of 268 mV at 10 mA cm−2 and a Tafel slope of 99.84 mV dec−1). The HER activity of Co(OH)2/MoS2/CC can be further promoted with an overpotential of 101 mV at 10 mA cm−2 due to the enhanced conductivity and exchange current density under light irradiation. Density functional theory calculations are carried out to gain a deeper insight into the effect of Co(OH)2MoS2 interface, indicating that the introduction of Co(OH)2 can reduce the energy barrier of the initial water dissociation process and provide the hydroxyl adsorption sites, while MoS2 can promote the adsorption of hydrogen intermediates and H2 release. The synergistic effect of light irradiation and interface engineering strategy can realize efficient hydrogen evolution reaction, which can enlighten and extend to other electrocatalytic system.