Precise Atomic Structure Regulation of Single-Atom Platinum Catalysts toward Highly Efficient Hydrogen Evolution Reaction.

Noble metal single-atom-catalysts (SACs) have demonstrated significant potential to improve atom utilization efficiency and catalytic activity for hydrogen evolution reaction (HER). However, challenges still remain in rationally modulating active sites and catalytic activities of SACs, which often results in sluggish kinetics and poor stability, especially in neutral/alkaline media. Herein, precise construction of Pt single atoms anchored on edge of 2D layered Ni(OH)2 (Pt-Ni(OH)2-E) is achieved utilizing in situ electrodeposition. Compared to the single-atom Pt catalysts anchored on the basal plane of Ni(OH)2 (Pt-Ni(OH)2-BP), the Pt-Ni(OH)2-E possesses superior electron affinity and high intrinsic catalytic activity, which favors the strong adsorption and rapid dissociation toward water molecules. As a result, the Pt-Ni(OH)2-E catalyst requires low overpotentials of 21 and 34 mV at 10 mA cm-2 in alkaline and neutral conditions, respectively. Specifically, it shows the high mass activity of 23.6 A mg-1 for Pt at the overpotential of 100 mV, outperforming the reported catalysts and commercial Pt/C. This work provides new insights into the rational design of active sites for preparing high-performance SACs.

Ultrathin Fe-ReS2 Nanosheets as Electrocatalysts for Accelerating Sulfur Reduction in Li-S Batteries.

Lithium-sulfur batteries are promising next-generation energy storage systems with high theoretical specific capacity. Despite extensive research efforts, it is still challenging to rationally design electrocatalysts with fast kinetics and effective adsorption of polysulfides. Herein, Fe-doped ReS2 (Fe-ReS2) ultrathin nanosheets are prepared as an electrocatalyst to trap the intermediates and accelerate the sulfur reduction reaction kinetics. Density functional theory calculations combined with activation energies in the multistep sulfur reduction reaction reveal that the Fe-ReS2 considerably reduces the activation energy and optimizes the optimum adsorption strength of polysulfides and catalytic activity. The Fe-ReS2/S exhibits a highly reversible discharge capacity of 882.3 mA h g-1 at 1 C. For 500 cycles, the capacity fade rate is 0.013% per cycle. Moreover, in situ Raman spectroscopy measurements further confirmed that both sulfur reduction and oxidation processes were significantly enhanced by Fe-ReS2.