Design of the Synergistic Rectifying Interfaces in Mott-Schottky Catalysts

The functions of interfacial synergy in heterojunction catalysts are diverse and powerful, providing a route to solve many difficulties in energy conversion and organic synthesis. Among heterojunction-based catalysts, the Mott-Schottky catalysts composed of a metal-semiconductor heterojunction with predictable and designable interfacial synergy are rising stars of next-generation catalysts. We review the concept of Mott-Schottky catalysts and discuss their applications in various realms of catalysis. In particular, the design of a Mott-Schottky catalyst provides a feasible strategy to boost energy conversion and chemical synthesis processes, even allowing realization of novel catalytic functions such as enhanced redox activity, Lewis acid-base pairs, and electron donor-acceptor couples for dealing with the current problems in catalysis for energy conversion and storage. This review focuses on the synthesis, assembly, and characterization of Schottky heterojunctions for photocatalysis, electrocatalysis, and organic synthesis. The proposed design principles, including the importance of constructing stable and clean interfaces, tuning work function differences, and preparing exposable interfacial structures for designing electronic interfaces, will provide a reference for the development of all heterojunction-type catalysts, electrodes, energy conversion/storage devices, and even super absorbers, which are currently topics of interest in fields such as electrocatalysis, fuel cells, CO₂ reduction, and wastewater treatment.

Mechanistic Insight into the Synergetic Interaction of Ammonia Borane and Water on ZIF-67-Derived Co@Porous Carbon for Controlled Generation of Dihydrogen

Regarding dihydrogen as a clean and renewable energy source, ammonia borane (NH₃BH₃, AB) was considered as a chemical H₂-storage and H₂-delivery material due to its high storage capacity of dihydrogen (19.6 wt %) and stability at room temperature. To advance the development of efficient and recyclable catalysts for hydrolytic dehydrogenation of AB with parallel insight into the reaction mechanism, herein, ZIF-67-derived fcc-Co@porous carbon nano/microparticles (cZIF-67_nm/cZIF-67_μm) were explored to promote catalytic dehydrogenation of AB and generation of H_2(g). According to kinetic and computational studies, zero-order dependence on the concentration of AB, first-order dependence on the concentration of cZIF-67_nm (or cZIF-67_μm), and a kinetic isotope effect value of 2.45 (or 2.64) for H₂O/D₂O identify the Co-catalyzed cleavage of the H-OH bond, instead of the H-BH₂NH₃ bond, as the rate-determining step in the hydrolytic dehydrogenation of AB. Despite the absent evolution of H_2(g) in the reaction of cZIF-67 and AB in the organic solvents (i.e., THF or CH₃OH) or in the reaction of cZIF-67 and water, Co-mediated activation of AB and formation of a Co-H intermediate were evidenced by theoretical calculation, infrared spectroscopy in combination with an isotope-labeling experiment, and reactivity study toward CO₂-to-formate/H₂O-to-H₂ conversion. Moreover, the computational study discovers a synergistic interaction between AB and the water cluster (H₂O)₉ on fcc-Co, which shifts the splitting of water into an exergonic process and lowers the thermodynamic barrier for the generation and desorption of H_2(g) from the Co-H intermediates. With the kinetic and mechanistic study of ZIF-67-derived Co@porous carbon for catalytic hydrolysis of AB, the spatiotemporal control on the generation of H_2(g) for the treatment of inflammatory diseases will be further investigated in the near future.

Highly enhanced H2 evolution of MoO3/g-C3N4 hybrid composites based on a direct Z-scheme photocatalytic system

A direct Z-scheme MoO₃/g-C₃N₄ heterojunction with appropriate oxygen vacancies is successfully fabricated via an in situ method of a one-pot pyrolysis strategy.