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A N, S co‐doped carbon with abundant vacancy defects (NSC) anchored Pt single atoms (SAs) and nanoclusters (NCs) derived from coal pitch by a self‐assembly‐pyrolysis strategy is reported and a defect‐induced electron redistribution effect based on Pt SAs‐Pt NCs/NSC catalyst is proposed for electrocatalytic hydrogen evolution reaction (HER). The optimized catalyst featuring Pt‐N3S1 SAs and Pt NCs dual active sites exhibit excellent HER activity with an overpotential of 192 mV at a current density of 400 mA cm−2, a turnover frequency of 30.1 s−1 at an overpotential of 150 mV, which the mass activity is 13716 mA mgPt−1, 7.4 times higher than that of 20% Pt/C catalyst. In situ Raman revealsa direct correlation between the defect structure of the catalyst and hydrogen adsorption during the reaction process. Density functional theory calculation shows the defect‐induced electron redistribution between Pt‐N3S1 SAs and Pt NCs. The electrons are transferred from Pt NCs to Pt SAs, which increases the number of electrons on the surface of Pt SAs and enhances the adsorption ability of H+. Meanwhile, the dissociation ability of H* on the Pt NCs is promoted, thus synergistically promoting the HER process. [ABSTRACT FROM AUTHOR]

The modulation effect manifests an encouraging potential to enhance the performance of single‐atom catalysts; however, the in‐depth study about this effect for the isolated diatomic sites (DASs) remains a great challenge. Herein, a proximity electronic effect (PEE) of Ni/Co DASs is proposed that is anchored in N‐doped carbon (N‐C) substrate (NiCo DASs/N‐C) for synergistic promoting electrocatalytic oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Benefiting from the PEE of adjacent Ni anchored by four nitrogen (Ni‐N4) moiety, NiCo DASs/N‐C catalyst exhibits superior ORR and HER activity. In situ characterization results suggest Co anchored by four nitrogen (Co‐N4) as main active site for O2 adsorption‐activation process, which promotes the formation of key *OOH and the desorption of *OH intermediate to accelerate the multielectron reaction kinetics. Theoretical calculation reveals the adjacent Ni‐N4 site as a modulator can effectively adjust the electronic localization of proximity Co‐N4 site, promoting the *OH desorption and *H adsorption on Co‐N4 site, thereby boosting ORR and HER process significantly. This study opens a new opportunity for rationally regulating the electronic localization of catalytic active centers by proximity single‐atom moiety, as well as provides guidance for designing high‐efficiency bifunctional electrocatalysts for promising applications. [ABSTRACT FROM AUTHOR]

Highly efficient electrocatalysts composed of earth‐abundant elements are desired for water‐splitting to produce clean and renewable chemical fuel. Herein, a heteroatomic‐doped multi‐phase Mo‐doped nickel phosphide/nickel sulfide (Mo‐NiPx/NiSy) nanowire electrocatalyst is designed by a successive phosphorization and sulfuration method for boosting overall water splitting (both oxygen and hydrogen evolution reactions (HER)) in alkaline solution. As expected, the Mo‐NiPx/NiSy electrode possesses low overpotentials both at low and high current densities in HER, while the Mo‐NiPx/NiSy heterostructure exhibits high active performance with ultra‐low overpotentials of 137, 182, and 250 mV at the current density of 10, 100, and 400 mA cm−2 in 1 m KOH solution, respectively, in oxygen evolution reaction. In particular, the as‐prepared Mo‐NiPx/NiSy electrodes exhibit remarkable full water splitting performance at both low and high current densities of 10, 100, and 400 mA cm−2 with 1.42, 1.70, and 2.36 V, respectively, which is comparable to commercial electrolysis. [ABSTRACT FROM AUTHOR]