As well known in the petroleum industry and academia, Ni/ZnO catalysts have excellent desulfurization performance. However, the sulfur transfer mechanism of reactive adsorption desulfurization (RADS) that occurs on Ni/ZnO catalysts remains controversial. Herein, a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system, and density functional theory calculations were performed to study the sulfur transfer process and the role of H₂ within the process. The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies (O_v) is more favorable than the hydrogenation of S to SH/H₂S on Ni and the subsequent H₂S desorption, and accordingly, H₂O is produced on Ni rather than on ZnO. Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_v formation on ZnO surface, which accounts for the presence of interfacial O_v in freshly prepared catalysts. Under RADS condition, hydrogenation of interfacial O atoms to form O−H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni, accompanied with the interfacial O_v generation. In contrast to the classic S transfer mechanism via H₂S, the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism. More importantly, the existence of interfacial O_v is an essential prerequisite for this interfacial S diffusion, and H₂ plays a key role in facilitating the O_v formation.

Large scale synthesis of high-efficiency bifunctional electrocatalyst based on cost-effective and earth-abundant transition metal for overall water splitting in the alkaline environment is indispensable for renewable energy conversion. In this regard, meticulous design of active sites and probing their catalytic mechanism on both cathode and anode with different reaction environment at molecular- scale are vitally necessary. Herein, a coordination environment inheriting strategy is presented for designing low-coordination Ni²⁺ octahedra (L-Ni-8) atomic interface at a high concentration (4.6 at.%). Advanced spectroscopic techniques and theoretical calculations reveal that the self-matching electron delocalization and localization state at L-Ni-8 atomic interface enable an ideal reaction environment at both cathode and anode. To improve the efficiency of using the self-modification reaction environment at L-Ni-8, all of the structural features, including high atom economy, mass transfer, and electron transfer, are integrated together from atomic-scale to macro-scale. At high current density of 500 mA/cm², the samples synthesized at gram-scale can deliver low hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) overpotentials of 262 and 348 mV, respectively.

The incorporation of small guest molecules or ions by bottom-up hydrothermal synthesis has recently emerged as a promising new way to engineer 1T-phase MoS₂ with high hydrogen evolution reaction (HER) activity. However, the mechanism of the associated structural evolution remains elusive and controversial, leading to a lack of effective routes to prepare 1T-phase MoS₂ with controlled structure and morphology, along with high purity and stability. Herein, urea is chosen as precursor of small molecules or ions to simultaneously engineer the phase (~16.4%, ~69.4%, and ~90.2% of 1T phase) and size (~98.8, ~151.6, and ~251.8 nm for the 90.2% 1T phase) of MoS₂ nanosheets, which represent an ideal model system for investigating the structural evolution in these materials, as well as developing a new type of 1T-phase MoS₂ arrays. Using reaction intermediate monitoring and theoretical calculations, we show that the oriented growth of 1T-phase MoS₂ is controlled by ammonia-assisted assembly, recrystallization, and stabilization processes. A superior HER performance in acidic media is obtained, with an overpotential of only 76 mV required to achieve a stable current density of 10 mA·cm^–2 for 15 h. This excellent performance is attributed to the unique array structure, involving well-dispersed, edge-terminated, and high-purity 1T-phase MoS₂ nanosheets.