Phase-dependent intermediate adsorption regulation on molybdenum carbides for efficient pH-universal hydrogen evolution

• Published in: Applied surface science 2023-07, Vol.625, Article 157169
• Main Authors: Guo, Peng, Wang, Maohuai, Zhang, Youzi, Wang, Yijin, Xin, Xu, Wang, Ruiling, Huang, Wenjing, Li, Xuanhua
• Format: Article
• Language: English
• Subjects: Hydrogen evolution reaction; Hydrogen intermediate adsorption regulation; Molybdenum carbides; Phase evolution engineering
• ISSN: 0169-4332
• DOI: 10.1016/j.apsusc.2023.157169

[Display omitted] •A phase evolution carbonization procedure for synthetic molybdenum carbides with tunable phases.•Tailoring optimal ΔGH* and water splitting energy barrier on molybdenum carbides.•An in-depth insight into their structure-activity relationship.•Mo2C/MoC-1 shows admirable HER performance in pH-universal conditions. Molybdenum carbides are the most promising noble metal-free electrocatalyst for hydrogen evolution reaction (HER). However, the investigation of phase-dependent intermediate adsorption on phase evolution engineering of molybdenum carbides is still insufficient. Herein, we developed a phase evolution carbonization procedure for synthetic molybdenum carbides with tunable phases for efficient hydrogen production, whose hydrogen intermediate adsorption energies can be regulated. Among them, Mo2C/MoC-1 shows a lowest overpotential of 128 mV, 162 mV and 119 mV in acidic, neutral and alkaline environment, respectively, steady operating at 10 mA cm−2 for 100 h. Tunable phase composites of molybdenum carbide composites induce favorable electronic structure and a local nucleophilic/electrophilic region at the interface of α-MoC and β-Mo2C phases, which promotes their HER performance. Density functional theory (DFT) calculations further reveal that Mo2C/MoC-1 conveys a Hads adsorption free energy (ΔGH*) of −0.17 eV in acid and a low water dissociation energy barrier of 1.12 eV in alkaline and neutral environment, pledging admirable HER performance in pH-universal conditions. This work provides a guidance to modulate the phase of molybdenum carbides for hydrogen evolution.