Exploring highly efficient non-noble-metal bifunctional catalysts for water electrolysis is vital for the commercial production of hydrogen.

Herein, a facile seed‐assisted strategy for preparing Cu nanoparticles (NPs) with polyvinyl pyrrolidone (PVP) capping is presented. Compared to the Cu NPs with deficient PVP protection, the Cu NPs capped with a sufficient amount of PVP remain almost completely as Cu0 species. In contrast, the Cu NPs that are considered PVP deficient form an oxide structure in which the inner layer is face‐centered cubic Cu and the outer layer is, at least in part, made up of Cu2O species. Furthermore, to eliminate CO2 molecule diffusion and simultaneously obtain significant current density (200 mA cm−2) for industrial applications, a flow cell configuration is used for carbon dioxide electro reduction reaction (CO2RR) testing in 0.5 m potassium hydroxide solution. The Cu NPs with zero valence deliver Faradaic efficiencies (FEs) for the CO2 reduction to CH4 of over 70%, with a current density exceeding 200 mA cm−2, outstripping the performances of the majority of the reported CO2 electrocatalysts. Interestingly, the distribution of products catalyzed by the Cu NPs with +1 valence includes multicarbon products (C2+) such as C2H4, C2H5OH, CH3COOH, and C3H7OH with combined FEs of >80%, with current densities of up to 300 mA cm−2. The above results unambiguously establish that surface oxidation of Cu species plays a crucial role in the CO2RR.

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The enhancement in the catalytic activity of PtM (transition metals, TMs) alloy nanoparticles (NPs) results from the electronic structure of Pt being modified by the TM. However, the oxidation of the TM would lead to the electronegativity difference between Pt and TM being much lowered, which induces a decrease in the number of electrons transferred from the TM to Pt, resulting in excessive oxygenated species accumulating on the surface of Pt, thus deteriorating their performance. In this work, the oxygen reduction reaction (ORR) performance of PtNi (PtNi) concave octahedral NPs (CONPs) in alkaline electrolytes is much improved by doping small amounts of phosphorus. The P-doped PtNi CONPs (P-PtNi) show about 2 and 10 times enhancement for ORR compared to PtNi and commercial Pt/C catalysts. The high-angle annular dark-field scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy mapping characterizations reveal that the P dopant uniformly distributes throughout the CONPs, Pt mainly locates at the edges and corners, whereas Ni situates at the center, forming a P-doped Pt-frame@Ni quasi-core-shell CONP. The X-ray photoelectron spectroscopy spectra indicate that the P dopant obviously increases the electron density of Pt compared with that of PtNi NPs, which contributes to the stabilization of the electronic structure of PtNi CONPs, thus restraining the excessive HO species produced on the catalysts, which endow them with a high catalytic performance in the ORR. In addition, the P attached to the Ni sites in the PtNi NPs partially prevents the Ni atoms being oxidized by the external O species, which is conducive to the structural and electrochemical stability of the PtNi NPs during the ORR. The present results provide a new insight into the development of ORR catalysts with low utilization of Pt.

Au nanorod (NR) which has strong LSPR (longitudinal surface plasmon resonance) effect in near-infrared (NIR) region was introduced into the Cu 7 S 4 hollow NPs to form Au NR@Cu 7 S 4 yolk−shell structured nanoparticles (YSNPs) for improving the photothermal property of NPs. The optimum photothermal conversion efficiency of the as-prepared YSNPs is 68.6%. The hybrid YSNPs had the highest photothermal property compared with the equivalent used Au NR and pure Cu 7 S 4 because of the synergistic effect of metal and semiconductor. In this case, the synergistic effect in YSNPs was discussed by tuning sizes of the YSNPs and the thickness of Cu 7 S 4 shell. The experimental results demonstrated that the NIR photoabsorption and the photothermal conversion performance of Au NR@Cu 7 S 4 YSNPs were much dependent on the geometric change of YSNPs, since the electrical field interaction between inner Au NR core and outer Cu 7 S 4 shell is closely effected by the distance of two materials and thickness of out-shell, as confirmed by the 3D finitedifference time domain simulation (FDTD) theory simulation. Moreover, we proved that the hollow yolk−shell structure of the YSNPs also endowed the NPs with a large potential in drug delivery.

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AgPt bimetallic hollow nanoparticles (AgPt-BHNPs) with an ultra-thin shell were synthesized.