Liquid H-2 storage systems based on organic molecules provide a feasible approach for the safe storage and transportation of hydrogen energy. However, the microstructure sensitivity of Pt catalysts for toluene hydrogenation leads to significant challenges in optimizing their catalytic performance. Herein, the d-band center of Pt nanoparticles regulated by controlling their electronic structures has been demonstrated as an effective parameter for modulating their catalytic activity for toluene hydrogenation. Mechanism investigations revealed that the downshift of the d-band center could weaken the adsorption of methylcyclohexane on the surface of Pt nanocatalysts, thereby facilitating the hydrogenation of toluene. The Pt/Al2O3 catalysts, with an optimized d-band center of -5.79 eV, exhibited the highest catalytic activity for toluene hydrogenation with a turnover frequency of 6693 h(-1) at 80 degrees C and 2 MPa H-2. This finding provides potential theoretical guidance for the rational design of Pt-based catalysts for toluene hydrogenation.

The long-term objective in the field of heterogeneous catalysis is to develop an enzyme-like catalytic pathway that can achieve exceptional catalytic performance even at low temperatures. Herein, we have demonstrated a heterogeneous oxidase-type catalysis on the ZnO-supported Ru clusters (Ru/ZnO) for efficient H-2 generation from an aqueous solution of formaldehyde (HCHO) at low temperatures. Due to its unique reaction pathway, the Ru/ZnO catalysts exhibited a temperature-insensitive activity for H-2 generation at the temperature of 15 to 45 degrees C. Remarkably, even at a low temperature of 5 degrees C, the Ru/ZnO catalysts still enabled an H-2 generation rate of 13.8 mmol gcat( -1) h(-1) with a turnover frequency (TOF) of 1678 h(-1). Additionally, instead of producing a CO2/CO molecule, the HCHO molecule underwent a transformation into formic acid and/or formate as the byproduct. This finding presents a novel class of heterogeneous catalysts to expand the potential application scenarios of liquid hydrogen storage and transportation systems.

Hydrogen production from organic hydrides represents a promising strategy for the development of safe and sustainable technologies for H-2 storage and transportation. Nonetheless, the majority of existing procedures rely on noble metal catalysts and emit greenhouse gases such as CO2/CO. Herein, we demonstrated an alternative N-doped carbon (CN) catalyst for highly efficient and robust H-2 production from an aqueous solution of formaldehyde (HCHO). Importantly, this process generated formic acid as a valuable byproduct instead of CO2/CO, enabling a clean H-2 generation process with 100% atom economy. Mechanism investigations revealed that the pyrrolic N in the CN catalysts played a critical role in promoting H-2 generation via enhancing the transformation of O-2 to generate (OO-)-O-center dot free radicals. Consequently, the optimized CN catalysts achieved a remarkable H-2 generation rate of 13.6 mmol g(-1) h(-1) at 30 degrees C. This finding is anticipated to facilitate the development of liquid H-2 storage and its large-scale utilization.

We report that the catalytic activity for benzoic acid hydrogenation to cyclohexanecarboxylic acid was positively correlated with the initial surface fraction of Pd2+ in the utilized Pd nanoparticles. Additionally, the mechanism for deactivation of Pd/C as a benzoic acid hydrogenation catalyst was proposed to involve a decrease in the Pd2+ fraction in a strongly reducing atmosphere.

Hydrogen spillover from the metal to the support opens a fresh avenue to design dual-active site catalysts for selective hydrogenation. However, very limited knowledge has been obtained to reveal the relationship between the capacity of hydrogen spillover and catalytic performance of hydrogenation. Herein, hydrogen spillover-dependent selective hydrogenation has been demonstrated on WO3-supported ppm-level Pd (PdHD/WO3), where the *H species generated and spilled from Pd to WO3 are readily utilized for addition of a reactant. The WO3 supports with a hexagonal phase and a suitable oxygen defect concentration can enhance the capacity of hydrogen spillover, significantly accelerating the catalytic activity of PdHD/WO3. For the hydrogenation of 4-chloronitrobenzene, the PdHD/WO3 catalysts with the highest capacity of hydrogen spillover yielded a turnover frequency (TOF) of 47,488 h-1 (33 times higher than that of traditional Pd/C). Meanwhile, benefiting from the hydrogen spillover, the unique adsorption of 4-chloronitrobenzene via the nitro group on the oxygen vacancy of WO3 guaranteed >99.9% selectivity of 4-chloroaniline during the whole hydrogenation. This work thus helps to create an effective method for fabricating cost-effective nanocatalysts with an extremely low Pd loading for the ideal hydrogenation with extremely high activity and selectivity.

Aqueous-phase reforming of methanol (APRM) represents an attractive approach for H2 storage and transportation. However, metals with high capacity of methanol activation generally exhibit poor capability for water dissociation and/or weak stabilization of *OH intermediates, leading to the unsatisfactory activity and unavoidable CO generation. Herein, we demonstrated that K+-doped Pt nanoparticles on & gamma;-Al2O3 (PtKx/Al2O3) stabilized the *OH intermediates on Pt surface, thereby achieving efficient H2 generation with ultra-low levels of CO through APRM at 120 degrees C. Mechanism investigations illustrated that K+ in Pt nanoparticles shifted the d-band center to stabilize the critical *OH generated from water dissociation without interference on methanol dissociation. Consequently, the PtKx/Al2O3 catalysts delivered a TOF of 142.3 h-1 with undetectable CO by gas chromatograph equipped with FID (detection limit: 5 ppm) at 120 degrees C. These findings are anticipated to promote methanol as a practical H2 carrier for the delivery of hydrogen with high purity.

The catalytic hydrogen transfer (CHT) cascade reaction between alcohols and nitro- compounds meets green chemistry yet involves high catalyst requirements. Herein, a hierarchical nano-pyramid structure, in which cobalt single atoms (Co SAs) are deposited on highly dispersed ZnO nanoparticles supported by nitrogen-doped carbon (denoted as Co-ZnO/NC), was designed and obtained through pyrolysis of ZnCo-ZIF. The catalyst exhibited excellent catalytic performance toward the CHT cascade reaction, achieving a high nitrobenzene conversion (94 %), imine selectivity (97 %), and turnover frequency (8.8 h-1). This nano-pyramid is a state-ofthe-art non-noble-metal catalyst and is comparable to noble-metal catalysts. Experimental and DFT results revealed that the Co SAs supported on ZnO reduced the reaction energy barrier of hydroxyl dehydrogenation, the first and rate-determining step in this heterogeneous catalysis. Furthermore, Co-ZnO/NC exhibits good recyclability and universality. Our findings offer a new catalyst for Schiff base synthesis and aid understanding of the roles of Zn in ZIF-derived carbon catalysts.

Probing the fundamental rules of different types of active sites on Pt nanoparticles is highly desirable for the rational design of catalysts. Herein, the function of each type of active site on Pt nanoparticles has been identified via investigating the hydrogenation in seven carbon-supported Pt nanoparticles with different sizes. Kinetic study and model calculations demonstrate that Pt edge atoms play a dominating role in H2 dissociation, while the hydrogenation of 6-chloroquinoline is achieved on the relatively flat Pt(111) and (100) atoms by activated H atoms spilled from Pt edge atoms. The optimized Pt nanoparticles with a size of 1.36 nm exhibit the highest number of edge atoms for the catalytic activity. Meanwhile, the increase in the Pt nanoparticles size results in a growing adsorption strength of 6-chloroquinoline, further leading to a reduction in the selectivity of the target product. The insights reported here may pave the way for the rational design of highly active and selective Pt nanoparticles for hydrogenation.

Hydrogen spillover on heterogeneous catalysts offers a new opportunity to improve catalytic hydrogenation. Due to the slow migration of hydrogen under mild conditions, hydrogen spillover-improved hydrogenation is still unsatisfactory on carbon material-supported metal nanoparticles. Herein, the modifying interface of carbon support-stimulated hydrogen spillover for hydrogenation has been successfully identified on the dual-active sites of Pt nanoparticles and modified carbon black (Pt/C-H2O2). The oxygen-containing-group-modified carbon black, which was achieved by a commonly used H2O2 treatment, not only triggered the efficient hydrogen migration along the carbon supports but also enhanced the adsorption of polar substrates, thus affording simultaneously enhanced catalytic activity and selectivity as well as stability. For probe reaction of 6-chloroquinoline hydrogenation to 6-chloro-1,2,3,4-tetrahydroquinoline, Pt/C-H2O2 catalysts yielded a 6.1 times higher catalytic activity with a high selectivity >99.5% than that on Pt/C with selectivity <96.0%. This work is anticipated to provide a facile and effective methodology for fabricating highly performed hydrogenation heterogeneous catalysts.

Ternary layered compound materials (bismuth oxyhalides and metal phosphorus trichalcogenides) stand out in electronic and optoelectronic fields due to their interesting physical properties. However, few studies focus on the preparation of high-quality two-dimensional (2D) BiOBr crystals with a typical layered structure, let alone their optoelectronic applications. Here, for the first time, high-quality 2D BiOBr crystals with ultrathin thicknesses (less than 10 nm) and large domain sizes (∼100 µm) were efficiently prepared via a modified space-confined chemical vapor deposition (SCCVD) method. It is demonstrated that a moderate amount of H2O molecules in the SCCVD system greatly promote the formation of high-quality 2D BiOBr crystals because of the strong polarity of H2O molecules. In addition, a linear relationship between the thickness of BiOBr nanosheets and Raman shift of $${\rm{A}}_{1{\rm{g}}}^{\left( 1 \right)}$$ mode was found. Corresponding theoretical calculations were carried out to verify the experimental data. Furthermore, the BiOBr-based photodetector was fabricated, exhibiting excellent performances with a responsivity of 12.4 A W−1 and a detectivity of 1.6×1013 Jones at 365 nm. This study paves the way for controllable preparation of high quality 2D BiOBr crystals and implies intriguing opportunities of them in op toelectronic applications.