Metal catalysts play an important role in the catalytic electrochemical processes and optimization of their performance is usually achieved through alloying with other metal atoms. Doping with interstitial hydrogen atoms is a special but effective way to regulate the electronic structure of host catalysts. Herein we demonstrate the intermixing of Pd and Rh atoms during the hydrogen-doping process of Pd@Rh core-shell nanocubes, forming an alloyed surface in Pd@Rh-H. The catalysts show enhanced performance in electrocatalytic methanol oxidation, as compared to commercial Pt/C and are even better than PdH@Rh core-shell nanocubes. The small structural differences between the two hydride catalysts are revealed by X-ray electron spectroscopy and pair distribution function analysis of electron diffraction. The theoretical calculation results show that Rh in Pd@Rh-H contains more negative charges than Rh in PdH@Rh, indicating more effective charge transfer in Pd@Rh-H. The d-band center (ε_d) of the Rh site in Pd@Rh-H shifts up, and the synergy between Rh and Pd optimizes the binding energy of CO and OH, inducing preferential catalytic activity. Our work provides guidance for the synthesis of high-performance catalysts by doping with interstitial atoms, which may provide a new strategy to fine-tune the electronic structure of other bimetallic nanoparticles.

Two-dimensional (2D) oxide can be continuously produced by bubbling oxygen into liquid metals and the harvesting of these oxide relies on the proper choice of dispersion solvents. The mass-production of ligand-free 2D materials from high melting-point metals will not be possible if the limited stability of the traditional dispersion solvents is not circumvented. Herein, liquid tin was used for the first time in the bubbling protocol and 2D tin oxide was obtained in molten salts. The nanosheets were studied with combined microscopic and spectroscopic techniques, and high-density grain boundaries was identified between the sub-5-nm nano-crystallites in the nanosheets. It gives rise to the high performance in electrocatalytic CO₂ reduction reaction. Density-functional-theory based calculation was applied to achieve a deeper understanding of the relationship between the activity, selectivity, and the grain- boundary features. The molten-salt based protocol could be explored for the synthesis of a library of functional 2D oxides.

Impeding high temperature sintering is challengeable for synthesis of carbon-supported single-atom catalysts (C-SACs), which requires high-cost precursor and strictly-controlled procedures. Herein, by virtue of the ultrastrong polarity of salt melts, sintering of metal atoms is effectively suppressed. Meanwhile, doping with inorganic sulfur anions not only produces sufficient anchoring sites to achieve high loading of atomically dispersed Co up to 13.85 wt.%, but also enables their electronic and geometric structures to be well tuned. When served as a cathode catalyst in dye-sensitized solar cells, the C-SAC with Co-N₄-S₂ moieties exhibits high activity towards the iodide reduction reaction (IRR), achieving a higher power conversion efficiency than that of conventional Pt counterpart. Density function theory (DFT) calculations revealed that the superior IRR activity was ascribed to the unique structure of Co-N₄-S₂ moieties with lower reaction barriers and moderate binding energy of iodine on the Co center, which was beneficial to I₂ dissociation.