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Converting CO2 to value‐added chemicals, e. g., CH3OH, is highly desirable in terms of the carbon cycling while reducing CO2 emission from fossil fuel combustion. Cu‐based nanocatalysts are among the most efficient for selective CO2‐to‐CH3OH transformation; this conversion, however, suffers from low reactivity especially in the thermodynamically favored low temperature range. We herein report ultrasmall copper (Cu) nanocatalysts supported on crystalline, mesoporous zinc oxide nanoplate (Cu@mZnO) with notable activity and selectivity of CO2‐to‐CH3OH in the low temperature range of 200–250 °C. Cu@mZnO nanoplates are prepared based on the crystal‐crystal transition of mixed Cu and Zn basic carbonates to mesoporous metal oxides and subsequent hydrogen reduction. Under the nanoconfinement of mesopores in crystalline ZnO frameworks, ultrasmall Cu nanoparticles with an average diameter of 2.5 nm are produced. Cu@mZnO catalysts have a peak CH3OH formation rate of 1.13 mol h−1 per 1 kg under ambient pressure at 246 °C, about 25 °C lower as compared to that of the benchmark catalyst of Cu−Zn−Al oxides. Our new synthetic strategy sheds some valuable insights into the design of porous catalysts for the important conversion of CO2‐to‐CH3OH. [ABSTRACT FROM AUTHOR]

Due to the surface inhomogeneity of the solid supports, direct growth of uniform bimetallic nanoparticles (NPs) with controllable structure and size thereon is particularly challenging. Herein, a surface‐confinement strategy is reported to directly prepare ultrafine bimetallic PtM NPs (MFe, Cu, and Co) with structure of core‐shell or intermetallic compounds on an N functionalized carbon support (NC). It is found that the N species of NC support can atomically disperse metal cations of precursors, which largely renders uniform nucleation and growth of bimetallic NPs and fine structure modulation of them. In another regard, metal transfer is confined to a narrow region on NC via N‐mediation, hence greatly favoring localized particle growth and formation of ultrafine bimetallic NPs. Remarkably, the ultrafine 3.1 ± 0.7 nm intermetallic Pt3Fe NPs on NC displayed excellent catalytic activity and durability toward electrochemical hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

• Under temperature reduction (UTR) was found in nanoalloy synthesis. • Stable, ultrasmall and clean Pd-based nanoalloys were synthesized through UTR. • Excellent ethanol electrooxidation and hydrogenation performances were achieved. We report a self-limiting growth method of ultrasmall Pd-containing bimetallic nanocatalysts supported on carbon through under temperature reduction (UTR). The UTR phenomenon is observed for the (co)reduction of a second base metal precursor (M = Co, Ni, and Zn) below its thermodynamic reduction temperature in the presence of Pd. The origin of the UTR phenomenon lies in the hydrogen spillover of Pd to drive the (co)reduction of the base metal at the temperature below its thermodynamic reduction temperature; while, the further reduction is shut down simultaneously to limit the overgrowth of nanoparticles when forming nanoalloys. Using nitrided carbon as a support, we demonstrate the self-limiting growth of three Pd-containing nanoalloys, including Pd 1.7 Co, Pd 1.6 Ni and Pd 2 Zn, with average sizes around 1.5 nm using UTR. Sub-2 nm Pd-containing bimetallic nanoalloys exhibited excellent catalytic properties in both methanol electrooxidation and selective hydrogenation of cinnamaldehyde. [ABSTRACT FROM AUTHOR]