Revealing the promoting effect of heterojunction on NiSx/MoO2 in urea oxidation assisted water electrolysis

• Published in: Journal of colloid and interface science 2025-03, Vol.682, p.180-187
• Main Authors: Hu, Yitao, Liu, Ruotong, Shu, Kaiqian, Dong, Yan, Li, Jihong, Wang, Tongzhou, Deng, Yida
• Format: Article
• Language: English
• Subjects: adsorption; catalysts; catalytic activity; clean energy; electrolysis; energy conservation; Heterostructure; hydrogen; Hydrogen production; oxidation; oxygen production; Transition metal dichalcogenides; urea; Urea oxidation reaction
• ISSN: 0021-9797; 1095-7103; 1095-7103
• DOI: 10.1016/j.jcis.2024.11.202

A heterojunction catalyst was synthesized by hydrothermal and gas-phase sulfidation methods, and UOR was used instead of OER and coupled with HER, resulting in excellent performance and stability. This performance is attributed to a heterostructure of NiSx/MoO2, which promotes charge transfer and the generation of active phases, as well as optimizes the selectivity of UOR. The stability originates from the redox reaction between NiOOH and urea in the electrolyte. [Display omitted] Investigating efficient non-precious metal-based catalysts for water electrolysis to produce hydrogen is a significant and urgent need in the field of clean energy technologies. Moreover, utilizing transition metal dichalcogenides (TMDs) to replace the oxygen evolution reaction (OER) with the urea oxidation reaction (UOR), coupled with the hydrogen evolution reaction (HER), is an effective energy-saving hydrogen production method. A heterostructure NiSx/MoO2 catalyst was prepared by a simple method, which exhibits excellent activity for UOR, requiring only 1.4 V to reach 100 mA cm−2. The high performance is attributed to the presence of the heterostructure, which effectively promotes charge redistribution and optimizes the electronic structure of the catalyst, thereby enhancing its adsorption capacity for intermediates. As a result, an electrolyzer assembled with NiSx/MoO2 as a bifunctional catalyst demonstrates excellent catalytic activity, ensures stability for over 200 h at a current density of 10 mA cm−2, and achieves a hydrogen production rate of 0.402 mmol h−1 at a potential of 1.8 V.