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

Coupling electrocatalytic water splitting (EWS) with benzyl alcohol (Ph-CH2OH) 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 ([email protected]/Ni3S2) were synthesized using a facile one-step electrodeposition technique. The [email protected]/Ni3S2 consists of ultrathin nanosheets (∼3.4 nm) with rich NiO/Ni3S2 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 [email protected]/Ni3S2 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-CH2OH oxidation is chosen as the corresponding anodic half-reaction instead of water oxidation, the [email protected]/Ni3S2 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 [email protected]/Ni3S2 as the cathode and anode electrocatalysts for HER and Ph-CH2OH oxidation, respectively, showing stable production of hydrogen fuels and value-added Ph-COOH. More importantly, the H2 generation rate is boosted by 2.6 times at 1.609 V by replacing water oxidation with Ph-CH2OH 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.