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Metal–support interaction is of great significance for catalysis as it can induce charge transfer between metal and support, tame electronic structure of supported metals, impact adsorption energy of reaction intermediates, and eventually change the catalytic performance. Here, we report the metal size-dependent charge transfer reversal, that is, electrons transfer from platinum single atoms to sulfur-doped carbons and the carbon supports conversely donate electrons to Pt when their size is expanded to ~1.5 nm cluster. The electron-enriched Pt nanoclusters are far more active than electron-deficient Pt single atoms for catalyzing hydrogen evolution reaction, exhibiting only 11 mV overpotential at 10 mA cm−2 and a high mass activity of 26.1 A mg−1 at 20 mV, which is 38 times greater than that of commercial Pt/C. Our work manifests that the manipulation of metal size-dependent charge transfer between metal and support opens new avenues for developing high-active catalysts., The charge transfer between metal and support is significant for catalysis, but little attention has been focused on charge transfer tuned by metal size. Here, authors report a metal size-dependent reversal of charge transfer between metal and carbon support in hydrogen evolution electrocatalysts.

Hierarchically porous carbons (HPCs) with multimodal pore systems exhibit great technological potentials, especially in the fields of heterogeneous catalysis, energy storage, and conversion. Here, we establish a simple and general approach to HPCs by carbonization of nonporous coordination polymers that are produced by mixing metal salts with polytopic ligands in alkaline aqueous solutions at room temperature. The proposed approach is applicable to a wide scope of ligand molecules (18 examples), thus affording the synthesized HPCs with high diversity in porosity, morphology, and composition. In particular, the prepared HPCs exhibit high specific surface areas (up to 2647 m2 g-1) and large pore volumes (up to 2.39 cm3 g-1). The HPCs-supported atomically dispersed Fe-Nx catalysts show much-improved fuel cell cathode performance over the micropore-dominated carbon black-supported catalysts, demonstrating the structural superiority of the HPCs for enhancing the mass transport properties.

Sulfur doped in carbon matrix can tether metal atoms to form high-loading atomically dispersed supported metal catalysts., Metals often exhibit robust catalytic activity and specific selectivity when downsized into subnanoscale clusters and even atomic dispersion owing to the high atom utilization and unique electronic properties. However, loading of atomically dispersed metal on solid supports with high metal contents for practical catalytic applications remains a synthetic bottleneck. Here, we report the use of mesoporous sulfur-doped carbons as supports to achieve high-loading atomically dispersed noble metal catalysts. The high sulfur content and large surface area endow the supports with high-density anchor sites for fixing metal atoms via the strong chemical metal-sulfur interactions. By the sulfur-tethering strategy, we synthesize atomically dispersed Ru, Rh, Pd, Ir, and Pt catalysts with high metal loading up to 10 wt %. The prepared Pt and Ir catalysts show 30- and 20-fold higher activity than the commercial Pt/C and Ir/C catalysts for catalyzing formic acid oxidation and quinoline hydrogenation, respectively.

Electrocatalysis of hydrogen evolution reaction (HER) in alkaline media is critical for the practical implementation of economical water-alkali electrolyzers. However, the sluggish water dissociation kinetics even on platinum-based electrocatalysts result in poor hydrogen-production activities. Here we report a structurally ordered Ir3V catalyst for efficiently catalyzing HER in alkaline media. The ordered Ir3V catalyst exhibits a low overpotential of 9.0 mV at 10 mA cm−2 in 1.0 M KOH electrolyte with Ir loading of 19 µg cm−2, corresponding a mass activity of 1200 A gIr−1 at the overpotential of 20 mV, which is 6.7, 9.4, and 3.3 times greater than that of the commercial Pt/C, Ir/C, and disordered Ir3V catalysts. The enhanced HER kinetics is ascribed to the charge redistribution on the ordered Ir3V surface with the maximized number of neighboring bimetallic Ir/V sites compared to the disordered solid solution counterpart, which promotes the water dissociation on the electron-deficient V sites.

A transition metal–assisted carbonization process can convert small organic molecules to functional carbon materials directly., Nanostructured carbon materials with large surface area and desired chemical functionalities have been attracting considerable attention because of their extraordinary physicochemical properties and great application potentials in catalysis, environment, and energy storage. However, the traditional approaches to fabricating these materials rely greatly on complex procedures and specific precursors. We present a simple, effective, and scalable strategy for the synthesis of functional carbon materials by transition metal–assisted carbonization of conventional small organic molecules. We demonstrate that transition metals can promote the thermal stability of molecular precursors and assist the formation of thermally stable polymeric intermediates during the carbonization process, which guarantees the successful preparation of carbons with high yield. The versatility of this synthetic strategy allows easy control of the surface chemical functionality, porosity, and morphology of carbons at the molecular level. Furthermore, the prepared carbons exhibit promising performance in heterogeneous catalysis and electrocatalysis.