Utilization and storage are the two main themes of green hydrogen. In hydrogen-involved system, development of highly active catalysts to achieve catalytic hydrogenation under mild conditions is a prerequisite for coupling with green hydrogen, so that green hydrogen with low outlet pressure can be directly used as a hydrogen source. To achieve this aim, we developed a high active Co-CoO_x@NC catalyst with metal/metal oxide induced by N-doping. The work function and Bader charge calculations reveal that N-doping can induce interfacial electrons rearrangement to form Co-CoO_x interface on the surface of Co nanoparticles (NPs). The interface is the dual active sites, where Co plays a role in H₂ dissociation and CoO_x can enhance the adsorption and activation of aldehyde compounds. Different from traditional dissimilar metal/oxide interface, the Co-CoO_x interface can effectively shorten hydrogen spillover distance and energy barrier, and thus exhibits high catalytic performance in hydrogenation of a variety of bio-derived aldehydes under aqueous-phase and mild reaction conditions that can couple with green hydrogen.

To data, using strong metal-support interaction (SMSI) effect to improve the catalytic performance of metal catalysts is an important strategy for heterogeneous catalysis, and this effect is basically achieved by using reducible metal oxides. However, the formation of SMSI between metal and inert-support has been so little coverage and remains challenge. In this work, the SMSI effect can be effectively extended to the inert support-metal catalysis system to fabricate a Cu⁰/Cu-doped SiO₂ catalyst with high dispersion and loading (38.5 wt.%) through the interfacial effect of inert silica. In the catalyst, subnanometric composite of Cu cluster and atomic copper (in the configuration of Cu–O–Si) can be consciously formed on the silica interface, and verified by extended X-ray absorption fine structure (EXAFS), in situ X-ray photoelectron spectroscopy (XPS), and high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) characterization. The promoting activity in transfer-hydrogenation by the SMSI effect of Cu-silica interface and the synergistic active roles of cluster and atomic Cu have also been revealed from surface interface structure, catalytic activity, and density functional theory (DFT) theoretical calculation at an atomic level. The subnanometric composite of cluster and atomic copper species can be derived from a facile synthesis strategy of metal-inert support SMSI effect and the realistic active site of Cu-based catalyst can also been identified accurately, thus it will help to expand the application of subnanometric materials in industrial catalysis.

Electrocatalytic synthesis of value-added chemicals is attracting significant research attention owing to its mild reaction conditions, environmental benignity, and potentially scalable application to organic synthetic chemistry. Herein, we report the preparation of a single-crystalline NiS₂ nanostructure film of ~ 50 nm thickness grown directly on a carbon fiber cloth (NiS₂/CFC) by a facile vapor-phase hydrothermal (VPH) method. NiS₂/CFC as an electrocatalyst exhibits activity for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER) in alkaline media. Furthermore, a series of alcohols (2-propanol, 2-butanol, 2-pentanol, and cyclohexanol) were electrocatalytically converted to the corresponding ketones with high selectivity, efficiency, and durability using the NiS₂/CFC electrode in alkaline media. In the presence of 0.45 M alcohol, a remarkably decreased overpotential (~ 150 mV, vs. RHE) at the NiS₂/CFC anode compared with that for water oxidation to generate O₂, i.e., the OER, in alkaline media leads to significantly improved H₂ generation. For instance, the H₂ generation rate in the presence of 0.45 M 2-propanol is almost 1.2-times of that obtained for pure water splitting, but in a system that employs an applied voltage at least 280 mV lower than that required for water splitting to achieve the same current density (20 mA·cm^–2). Thus, our results demonstrate the applicability of our bifunctional non-precious-metal electrocatalyst for organic synthesis and simultaneous H₂ production.

A chitosan-polyvinyl alcohol (CS/PVA) co-polymer substrate possessing a large number of amino and hydroxyl groups is used as a substrate to induce the direct growth and in situ sequential transformation of titanate crystals under HF vapor phase hydrothermal conditions. The process involves four distinct formation/transformation stages. HTiOF₃ crystals with well-defined hexagonal shapes are formed during stage I, and are subsequently transformed into {001} faceted anatase TiO₂ crystal nanosheets during stage II. Interestingly, the formed anatase TiO₂ crystals are further transformed into cross-shaped and hollow squareshaped HTiOF₃ crystals during stages III and IV, respectively. Although TiO₂ crystal phases and facet transformations under hydrothermal conditions have been previously reported, in situ crystal transformations between different titanate compounds have not been widely reported. Such crystal formation/transformations are likely due to the presence of large numbers of amino groups in the CS/PVA substrate. When celluloses possessing only hydroxyl groups are used as a substrate, the direct formation of {001} faceted TiO₂ nanocrystal sheets is observed (rather than any sequential crystal transformations). This substrate organic functional group-induced crystal formation/transformation approach could be applicable to other material systems.