Engineering 2D NiO/Ni3S2 heterointerface electrocatalyst for highly efficient hydrogen production coupled with benzyl alcohol oxidation

Abstract

• CC@NiO/Ni 3 S 2 was efficiently developed by a facile one-step electrodeposition. • NiO/Ni 3 S 2 interfaces induce the charge redistribution to enhance catalytic activity. • CC@NiO/Ni 3 S 2 shows a bifunctional catalytic activity for HER and Ph-CH 2 OH oxidation. • A two-electrode electrolyzer with an electrical energy saving of 10.0 % is constructed. Coupling electrocatalytic water splitting (EWS) with benzyl alcohol (Ph-CH 2 OH) oxidation can efficiently suppress the sluggish water oxidation and boost hydrogen production efficiency. However, it remains an enormous challenge to design the corresponding bifunctional electrocatalysts with high activity, high selectivity, and long-term stability. Herein, 2D Ni-based nanoarrays grown directly on carbon cloth (CC) substrate (CC@NiO/Ni 3 S 2 ) were synthesized using a facile one-step electrodeposition technique. The CC@NiO/Ni 3 S 2 consists of ultrathin nanosheets (∼3.4 nm) with rich NiO/Ni 3 S 2 heterointerfaces, which not only efficiently exposes more active sites and accelerates mass/charge diffusion, but also provides unique interfacial interactions for charge redistribution to activate the formation of key reaction intermediates. As a result, the CC@NiO/Ni 3 S 2 exhibits a low overpotential of 91 mV at 10 mA cm −2 with high catalytic stability for catalyzing hydrogen evolution reaction (HER). When the Ph-CH 2 OH oxidation is chosen as the corresponding anodic half-reaction instead of water oxidation, the CC@NiO/Ni 3 S 2 also shows an excellent catalytic activity as well as a high selectivity (over 98%) towards benzoic acid (Ph-COOH), which is a value-added chemical and can be easily separated by crystallization. A two-electrode electrolyzer was accordingly constructed using CC@NiO/Ni 3 S 2 as the cathode and anode electrocatalysts for HER and Ph-CH 2 OH oxidation, respectively, showing stable production of hydrogen fuels and value-added Ph-COOH. More importantly, the H 2 generation rate is boosted by 2.6 times at 1.609 V by replacing water oxidation with Ph-CH 2 OH oxidation, which can also save electrical energy of 10.0 % at 50 mA cm −2 . This work offers a facile strategy to develop advanced bifunctional electrocatalysts with abundant heterointerfaces for practical applications in energy-saving hydrogen production.