Defect engineering is widely applied in transition metal dichalcogenides (TMDs) to achieve electrical, optical, magnetic, and catalytic regulation. Vacancies, regarded as a type of extremely delicate defect, are acknowledged to be effective and flexible in general catalytic modulation. However, the influence of vacancy states in addition to concentration on catalysis still remains vague. Thus, via high throughput calculations, the optimized sulfur vacancy (S-vacancy) state in terms of both concentration and distribution is initially figured out among a series of MoS2 models for the hydrogen evolution reaction (HER). In order to realize it, a facile and mild H2O2 chemical etching strategy is implemented to introduce homogeneously distributed single S-vacancies onto the MoS2 nanosheet surface. By systematic tuning of the etching duration, etching temperature, and etching solution concentration, comprehensive modulation of the S-vacancy state is achieved. The optimal HER performance reaches a Tafel slope of 48 mV dec–1 and an overpotential of 131 mV at a current density of 10 mA cm–2, indicating the superiority of single S-vacancies over agglomerate S-vacancies. This is ascribed to the more effective surface electronic structure engineering as well as the boosted electrical transport properties. By bridging the gap, to some extent, between precise design from theory and practical modulation in experiments, the proposed strategy extends defect engineering to a more sophisticated level to further unlock the potential of catalytic performance enhancement.

Perovskites (ABX3) are promising oxygen evolution reaction (OER) catalysts for their highly intrinsic activity. The in‐depth understanding and the adjustment of dynamic reconstruction of active phases for perovskites in OER are still a daunting challenge. Here, a refined A‐site management strategy is proposed for perovskite oxides, which facilitates the surface reconstruction of the B‐site element based active phase to enhance the OER performance. Electrocatalyst LaNiO3 displays a dynamic reconstruction feature during OER with the growth of a self‐assembled NiOOH active layer, based on the in situ electrochemical Raman technology. Precise A‐site Ce doping lowers the reconstruction potential for the active phase and the dynamic structure–activity correlation is well established. Theoretical calculations demonstrate that A‐site Ce substitution upshifts the O 2p level for greater structural flexibility with optimized oxygen vacancy content, thereby activating the B‐site atom and promoting the active phase reconstruction. These results suggest that A‐site management prompts the B‐site element based active phase dynamic reconstruction via engineered X‐site content as a bridge. Therefore, indicating the strong correlation of each‐site component in perovskite oxides during OER and deepening the understanding of the fundamental processes of the structural transformation and further benefiting the accurate design of high‐efficiency perovskite OER electrocatalysts.

Black phosphorus (BP) nanosheet (NS) is an emerging oxygen evolution reaction (OER) electrocatalyst with both high conductivity and abundant active sites. However, its ultrathin structure suffers instability because of the lone pair electrons exposed at the surface, which badly restricts durability for achieving long‐term OER catalysis. Herein, a facile solvothermal reduction route is designed to fabricate Co/BP NSs hybrid electrocatalyst by in situ growth of cobalt nanoparticles on BP NSs. Notably, electronic structure engineering of Co/BP NSs catalyst is observed by electron migration from BP to Co due to the higher Fermi level of BP than that of Co. Because of the preferential migration of the active lone pairs from the defect of BP NSs, the stability and high hole mobility can be effectively retained. Consequently, Co/BP NSs electrocatalyst exhibits outstanding OER performance, with an overpotential of 310 mV at 10 mA cm−2, and excellent stability in alkaline media, indicating the potential for the alternatives of commercial IrO2. This study provides insightful understanding into engineering electronic structure of BP NSs by fully utilizing defect and provides a new idea to design hybrid electrocatalysts.

Photoelectrochemical water splitting via consumption of solar energy is considered an alternative approach to address both fossil resource and global warming issues. On the basis of the bottom‐up technique, major strategies have been developed to enrich the complexity of nanostructures by incorporating various functional components to realize outstanding photoelectrochemical (PEC) performance for hydrogen evolution, such as high solar‐to‐hydrogen efficiency and long‐term stability. In such a PEC system, each nanomaterial component individually, and more importantly, together with the formed interfaces, contributes to PEC performance elevation. Specifically, the two types of interfaces that have emerged, i.e., the interfaces between photoelectrodes and electrolytes (solid–liquid contact) and the interfaces inside photoelectrodes (solid–solid contact), have both been effectively engineered to facilitate charge separation and transportation and even enhance the antiphotocorrosion properties. A comprehensive understanding, summary, and review of such interface engineering protocols may provide novel and effective approaches for PEC system designing.

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The voltammetric responses of Pt disk electrodes 5-50 nm in radii in the presence of excess inert electrolyte were investigated to verify the applicability of the conventional diffusion-based voltammetric theory to nanoscale electrochemical interfaces. A so-called "inverted heat-sealing" procedure was introduced in the electrode fabrication process to eliminate the possible tiny interstice between the glass sheath and electrode wire that could severely distort the voltammetric curves of nanometer-szied electrodes. Linear relations between the limiting currents (i L ) and the concentrations of electroactive ions (c a ) were found at electrodes as small as 5 nm, seemingly inferring that the classic voltammetric theory is applicable at such small electrodes. However, a delicate analysis on the dependences of i L on the electroactive size of electrode and the charge carried by the electroactive ions revealed that the i L ∼ c a linearity is altered from the predication of the conventional voltammetric theory as the size of electrode approaches nanometer scales (e. g., <10 nm). The altered i L ∼ c a linearity at nanoelectrodes is explainable in terms of size-induced merging of electric double layer (EDL) and concentration depletion layer (CDL) and is well-predictable from the previous dynamic double layer model for nanoelectrode based on Poisson-Nernst-Planck theory (J. Phys. Chem. B 2006, 110, 3262). It is thus concluded that the enhanced EDL effects at nanoscale electrochemical interfaces do cause deviations from the predication of the conventional voltammetric theory, but the deviations are quantitatively small (e.g., within 20% even at electrodes of a few nanometers) and in most cases might be hardly distinguished with the experimental uncertainties.

We report a universal phase reconfiguration phenomenon and a doping strategy to enhance the activity of multivalent nickel sulfides in hydrogen evolution. Based on these, a life-time dynamic structure-activity correlation has been established.

Identifying the relationship between catalytic performance and material structure is crucial to establish the design principle for highly active catalysts. Deficiency in BO bond covalency induced by lattice distortion severely restricts the oxygen reduction reaction (ORR) performance for ABO3‐type perovskite oxides. Herein, a rearrangement of hybridization mode for BO bond is used to tune the overlap of the electron cloud between B 3d and O 2p through A‐stie doping with larger radius ions. The BO bond covalency is strengthened with a BOB bond angle recovered from intrinsic structural distortion. As a result, the adsorption and the reduction process for O2 on the oxide surface can be promoted via shifting the O‐2p band center toward the Fermi Level. Simultaneously, the spin electrons in the Mn 3d orbit become more parallel. It will lead to a high electrical conductivity by the enhanced double exchange process and thereof mitigate the ORR efficiency loss. Further density functional theory calculation reveals that a flat [BO2] plane will make contribution to the charge transfer process from lattice oxygen to adsorbed oxygen (mediated with B ions). Through such exploration of the effect of crystal structure on the electronic state of perovskite oxides, a novel insight into design of highly active ORR catalysts is offered.