Developing low‐cost and high‐efficiency catalysts for sustainable hydrogen production through electrocatalytic hydrogen evolution reaction (HER) is crucial yet remains challenging. Here, a strategy is proposed to fill Ni‐vacancy (Niv) sites of dual‐deficient NiO (D‐NiO‐Pt) deliberately created by Ar plasma with homogeneously distributed Pt atoms driven by oxygen vacancies (Ov). The incorporated Pt atoms filling the Niv reduce the formation energy to increase crystal stability, and subsequently combine with additional Ov to tune the electronic structure of the surrounding Ni sites. Thus, a more ideal hydrogen adsorption free energy (ΔGH*) closer to 0 of Ni sites and Pt sites can be achieved. As a result, the D‐NiO‐Pt electrode achieves superior mass activity of ≈1600 mA mg−1 (normalized by platinum) and nearly negligible loss of activity during long‐term operation, which is much better than as‐prepared Pt‐containing NiO catalysts without plasma treatment. A low overpotential of 20 mV is required for the D‐NiO‐Pt at 10 mA cm−2 in alkaline HER, outperforming that of the commercial Pt/C. In addition, the universal access to the other Ni‐based compounds including nickel phosphide (Ni2P), nickel sulfide (Ni0.96S), and nickel selenide (NiSe2) is also demonstrated by employing a vacancy‐driven Pt filling mechanism.

We design V doped NiCoP nanosheets with P vacancies induced by Ar plasma as a cost-effective and bifunctional electrocatalyst for overall water splitting.

Vertical-standing arrays have aroused great enthusiasm as electrode materials for supercapacitors in recent years owing to their structural and compositional characteristics. Although significant efforts have been made in the construction of vertical-standing arrays with tailored compositions and architectures, an in-depth understanding of the relevant structure-activity relationships has not yet been reviewed in detail. Herein, recent important progress in controllably synthesizing vertical-standing arrays as well as their application as supercapacitors is reviewed. Afterward, promising strategies to improve the electrochemical performance of vertical-standing arrays are discussed. Finally, the challenges and possible directions for developing vertical-standing arrays with outstanding performance are outlined. This review provides important guidelines for designing and regulating verticalstanding arrays and constructing desirable electrode materials for future electrochemical energy storage.

HIGHLIGHTS • Freestanding Mo-doped NiCoP nanosheets are designed as bifunctional electrocatalysts for overall water splitting. • Remarkable electrocatalytic performances are achieved by Mo doping, where a low-water-splitting voltage of 1.61 V at 10 mA cm −2 is obtained.

We report a facile synthesis strategy for core-branched CoSe2/Ni0.85Se nanotube arrays directly on Ni foam by simply selenizing Co-precursor nanowires.