Fig. 1. (a) Illustration of catalytic mechanism on Au/TiO2/Pt sandwich nanostructures. (b) Transmission electron microscopy (TEM) image of a TiO2 nanoparticle monolayer. (c) Elemental mapping of the Au/TiO2/Pt sandwich nanostructure using a focused ion beam (FIB) system. Scale bar: 50 nm. Reprinted with permission from Ref. [53]. Copyright 2024, John Wiley and Sons.

Fig. 2. (a) Schematic illustration of the catalysts. Semi-sectional and cross-sectional views of the different catalysts prepared by ALD. The yellow and black balls represent Pt and CoOx, respectively. (b) The possible enhancement mechanism for the selective catalytic atomic layer deposition (CALD) hydrogenation reaction. Reprinted with permission from Ref. [54]. Copyright 2019, Springer Nature.

Fig. 3. (a) Reaction network of the hydrogenation of nitrobenzene. (b) Schematic illustration of four catalysts, including Ru/Pd/MCMOS, Pd/MCMOS, Ru/MCMOS, and Ru-Pd/DSNs. (c) Product distributions of the sequential hydrogenation over different catalysts. (d) Schematic illustration for neighboring metal-assisted hydrogenation over Ru/Pd/MCMOS. Reprinted with permission from Ref. [55]. Copyright 2021, Springer Nature.

Fig. 4. (a) Atomic-resolution HAADF-STEM images of Au@1ML-Pt. (b) Comparison of the rates of p-CAN formation on platinum, gold, AuPt alloy, and Au@Pt core-shell catalysts. (c) Highlight of the shifts in platinum 4f7/2 binding energy with platinum particle size and composition normalized to that of bulk platinum. (d) Arrhenius plots of Au@1ML-Pt and 2.7 nm-Pt catalysts for the hydrogenation of p-CNB. (e) Stability testing of the catalyst. Reprinted with permission from Ref. [56]. Copyright 2021, Springer Nature.

Fig. 5. (a) Illustration of Pd1/TiO2, PdNPs/TiO2, and Pd1+NPs/TiO2. (b) Kinetic curves of Pd1/TiO2 (green circle), PdNPs/TiO2 (blue square), and Pd1+NPs/TiO2 (magenta triangle) at 25 °C under 1 atm H2 in the MAP hydrogenation reaction. (c) Proposed catalytic mechanism of the synergistic catalyst Pd1+NPs/TiO2. Reprinted with permission from Ref. [70]. Copyright 2020, Springer Nature.

Fig. 6. (a) Catalytic performance of Ir/CMK before and after SCN added. (b) lsotopic effect in quinoline. (c) Proposed synergistic mechanism of Ir1+NPs/CMK catalyst for the hydrogenation of quinoline. Reprinted with permission from Ref. [71]. Copyright 2022, Springer Nature.

Fig. 7. (a) Reaction process of carbonyl reductive amination and the synergistic reaction mechanism of Co1+NPs catalyzing the process. (b) Time-yield plots in reductive amination of cyclohexanone over Co@C-N(800). Reaction conditions: 1 mmol cyclohexanone, 3 mL methanol, 35 °C, Co@C-N(800), 50 mg (29.2 mol% Co), 1.4 MPa H2 and 0.6 MPa NH3. Reprinted with permission from Ref. [73]. Copyright 2022, Royal Society of Chemistry.

Fig. 8. (a) Catalytic performance of cyclohexanol dehydrogenation reaction over Rh1/ND@G, Rh1+n/ND@G, and Rhp/ND@G catalysts. (b) Metal-normalized activity of cyclohexanol-to-cyclohexanone (above) and cyclohexanone-to-phenol (below) steps over the catalysts Rh1/ND@G, Rh1+n/ND@G, and Rhp/ND@G. Reprinted with permission from Ref. [72]. Copyright 2022, American Chemical Society.

Fig. 9. (a) Illustration depicting the CAL hydrogenation reaction. (b) Comparison of turnover frequency (TOF) values for PdSA/g-C3N4, PdSA+C/g-C3N4, and PdNPs/g-C3N4. (c) Stability tests results. (d) Diagram presenting the reaction mechanism. Reprinted with permission from Ref. [74]. Copyright 2024, American Chemical Society.

Fig. 10. (a) Schematic diagram illustrating the catalytic mechanism of dual single-atom catalyst Ir1Mo1/TiO2 cooperatively catalyzing the highly selective hydrogenation of nitrostyrene to aminostyrene. Reprinted with permission from Ref. [75]. Copyright 2021, American Chemical Society. (b) Mechanism diagram of catalytic hydrogenation of p-chloronitrobenzene over Pt1Fe1/ND catalyst. Reprinted with permission from Ref. [76]. Copyright 2023, John Wiley and Sons.

Fig. 11. (a) Schematic illustration of the synthesis and structure of Ru/TiO2@TP-TTA and 1. (b) Conversion rates of NAD+ hydrogenation with various catalysts. (c) Rational mechanism for NAD(P)+ hydrogenation over homogeneous-heterogeneous coupling catalysts. Reprinted with permission from Ref. [80]. Copyright 2022, Springer Nature. (d) Schematic representation of the fabrication of an integrated core-shell nanoreactor comprising Ni NPs and Rh composites. (e) Comparative activities of aldehyde ketone reductase (AKR) in the presence of free and immobilized Rh complexes during the asymmetric hydrogenation of acetophenone. Reprinted with permission from Ref. [81]. Copyright 2023, John Wiley and Sons.

Fig. 12. (a) Schematic diagram of the structure of Ru catalyst modified with different organic ligands. (b) The catalytic performance of Ru NPs in hydrogenation of BA using hexane as solvent. (c) The calculated H-bonding energies between BA and PPh3, NH2, and Si-OH, respectively. Reprinted with permission from Ref. [87]. Copyright 2019, John Wiley and Sons.

Fig. 13. (a) Synthesis of Py-COF and Be-COF. (b) Conversion and phenyl ethanol selectivity in acetophenone (AP) hydrogenation over Pd NPs catalyst. (c) Reaction profiles of Pd NPs in AP hydrogenation. (d) Reaction mechanism of Pd/ Py-COF catalyzed AP hydrogenation. Reprinted with permission from Ref. [89]. Copyright 2022, Springer Nature.

Fig. 14. (a,b) Reaction kinetics of various Pt/COF/SiO2 catalysts in acetophenone (AP) hydrogenation. (c) Illustration of the catalytic mechanism of Pt/COF/SiO2 facilitating the hydrogenation of AP to produce alcohol. Reprinted with permission from Ref. [90]. Copyright 2022, American Chemical Society.