Nickel-based electrocatalysts are promising candidates for oxygen evolution reaction (OER) but suffer from high activation overpotentials. Herein, in situ structural reconstruction of V-doped Ni 2 P pre-catalyst to form highly active NiV oxyhydroxides for OER is reported, during which the partial dissolution of V creates a disordered Ni structure with an enlarged electrochemical surface area. Operando electrochemical impedance spectroscopy reveals that the synergistic interaction between the Ni hosts and the remaining V dopants can regulate the electronic structure of NiV oxyhydroxides, which leads to enhanced kinetics for the adsorption of *OH and deprotonation of *OOH intermediates. Raman spectroscopy and X-ray absorption spectroscopy further demonstrate that the increased content of active β-NiOOH phase with the disordered Ni active sites contributes to OER activity enhancement. Density functional theory calculations verify that the V dopants facilitate the generation of *O intermediates during OER, which is the rate-determining step for realizing efficient O 2 evolution. Optimization of these properties endows the NiV oxyhydroxide electrode with a low overpotential of 221 mV to deliver a current density of 10 mA cm −2 and excellent stability in the alkaline electrolyte.

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Hierarchical porous Fe3O4 particles with tunable grain size were synthesized based on a facile poly (diallyldimethylammonium chloride) (PDDA)-modulated solvothermal method. The products were characterized with scanning electron microscopy (SEM) and transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N2 adsorption-desorption technique, vibrating sample magnetometer (VSM), and dynamic light scattering (DLS). The results show that increasing the PDDA dosage decrease the grain size and particle size, which increased the particle porosity and enhanced the surface area from 7.05 to 32.75 m(2) g(-1). Possible mechanism can be ascribed to the PDDA function on capping the crystal surface and promoting the viscosity of reaction medium to mediate the growth and assembly of grain. Furthermore, the arsenic adsorption application of the as-obtained Fe3O4 samples was investigated and the adsorption mechanism was proposed. High magnetic Fe3O4 particles with increased surface area display improved arsenic adsorption performance, superior efficiency in low-level arsenic removal, high desorption efficiency, and satisfactory magnetic recyclability, which are very promising compared with commercial Fe3O4 particles.

Transition metal nitrogen carbon based single‐atom catalysts (SACs) have exhibited superior activity and selectivity for CO2 electroreduction to CO. A favorable local nitrogen coordination environment is key to construct efficient metal‐N moieties. Here, a facile plasma‐assisted and nitrogen vacancy (NV) induced coordinative reconstruction strategy is reported for this purpose. Under continuous plasma striking, the preformed pentagon pyrrolic N‐defects around Ni sites can be transformed to a stable pyridinic N dominant Ni‐N2 coordination structure with promoted kinetics toward the CO2‐to‐CO conversion. Both the CO selectivity and productivity increase markedly after the reconstruction, reaching a high CO Faradaic efficiency of 96% at mild overpotential of 590 mV and a large CO current density of 33 mA cm‐2 at 890 mV. X‐ray adsorption spectroscopy and density functional theory (DFT) calculations reveal this defective local N environment decreases the restraint on central Ni atoms and provides enough space to facilitate the adsorption and activation of CO2 molecule, leading to a reduced energy barrier for CO2 reduction.

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