MaLian

Isolated heterogeneous single-site catalysts have been attracted great interest in diverse catalytic reactions because of their uniform and distinct geometric and electronic structure. Among various porous supports, metal-organic frameworks (MOFs), with molecular level structure control and modularity, offer the versatile platforms for supporting isolated single-site catalysts. Owing to the well-defined anchoring sites lying in the nodes, ligands or nanopores of MOFs, the single-site catalysts could be grafted precisely without protection by bulky ligands. More interestingly, together with the nanopore confinement effect of MOFs, single-site catalysts could exhibit the excellent performances in terms of catalytic activity, selectivity and stability. In this review, we focus on summarizing the recent advances in the precise design, synthesis, characterization and catalytic applications of isolated single-site catalysts supported by MOFs and elucidating the relationship between structure and performance of single-site catalysts. Finally, we give a perspective on controllable synthesis of isolated single-site catalysts supported by MOFs as well as their catalytic applications.

Global consumption of fossil fuels is driving anthropogenic climate change and depleting reserves. To stem these environmental problems and secure future energy commodities, the electrochemical CO₂ reduction reaction (CO₂RR) presents an ideal solution because it can couple carbon-capture storage technology with renewable energy to convert atmospheric CO₂ into useful chemical feedstocks. Efficient catalysts are required to drive this process with adequate energy efficiency and product selectivity. In this review, we discuss how surface and interfacial engineering can be used as a strategy for designing copper alloy and bimetallic materials for selective CO₂ reduction to CO or hydrocarbons and alcohols.

The electrochemical CO₂ reduction reaction (CO₂RR) can couple carbon-capture storage with renewable energy to convert CO₂ into chemical feedstocks. For this process, copper is the only metal known to catalyze the CO₂RR to hydrocarbons with adequate efficiency, but it suffers from poor selectivity. Copper bimetallic materials have recently shown an improvement in CO₂RR selectivity compared with that of copper, such that the secondary metal is likely to play an important role in altering inherent adsorption energetics. This review explores the fundamental role of the secondary metal with a focus on how oxygen (O) and hydrogen (H) affinity affect selectivity in bimetallic electrocatalysts. Here, we identify four metal groups categorized by O and H affinities to determine their CO₂RR selectivity trends. By considering experimental and computational studies, we link the effects of extrinsic chemical composition and physical structure to intrinsic intermediate adsorption and reaction pathway selection. After this, we summarize some general trends and propose design strategies for future electrocatalysts.