Oxygen evolution reaction is critical for water splitting or metal-air batteries, but previous research mainly focuses on electrode material or structure optimization. Herein, we demonstrate that surfactant modification of a NiFe layered double hydroxide (LDH) array electrode, one of the best catalysts for oxygen evolution reaction (OER), could achieve superaerophobic surface with balanced surface charges, affording fast mass transfer, quick gas release, and boosted OER performance. The assembled surfactants on the electrode surface are responsible for lowering the bubble adhesive force (~ 1.03 μN) and corresponding fast release of small bubbles generated during OER. In addition, the bipolar nature of the hexadecyl trimethyl ammonium bromide (CTAB) molecule lead to bilayer assembly of the surfactants with the polar ends facing the electrode surface and the electrolyte, resulting in neutralized charges on the electrode surface. As a result, OH^- transfer was facilitated and OER performance was enhanced. With the modified superaerophobic surface and balanced surface charge, NiFe LDHs-CTAB nanostructured electrode showed ultrahigh current density increase (9.39 mA/(mV cm²)), 2.3 times higher than that for conventional NiFe LDH nanoarray electrode), dramatically fast gas release, and excellent durability. The introduction of surfactants to construct under-water superaerophobic electrode with in-time repelling ability to the as-formed gas bubbles may open up a new pathway for designing efficient electrodes for gas evolution systems with potentially practical application in the near future.

Electrocatalytic CO₂ reduction is a promising way to mitigate the urgent energy and environmental issues, but how to increase the selectivity for desired product among multiple competing reaction pathways remains a bottleneck. Here, we demonstrate that engineering the gas–liquid–solid contact interface on the electrode surface could tailor the selectivity of CO₂ reduction and meanwhile suppress H₂ production through regulated reaction kinetics. Specifically, polytetrafluoroethylene (PTFE) was utilized to modify a Cu nanoarray electrode as an example, which is able to change the electrode surface from aerophobic to aerophilic state. The enriched nano-tunnels of the Cu nanoarray electrode can facilitate CO₂ transportation and pin gaseous products on the electrode surface. The latter is believed to be the reason that boosts the Faradaic efficiency of liquid products by 67% and limits the H₂ production to less than half of before. This interface engineering strategy also lowered H₂O (proton) affinity, therefore promoting CO and HCOOH production. Engineering the electrode contact interface controls the reaction kinetics and the selectivity of products, which should be inspiring for other electrochemical reactions.

Atomic composition tuning and defect engineering are effective strategies toenhance the catalytic performance of multicomponent catalysts by improvingthe synergetic effect; however, it remains challenging to dramatically tune the active sites on multicomponent materials through simultaneous defect engineeringat the atomic scale because of the similarities of the local environment. Herein, using the oxygen evolution reaction (OER) as a probe reaction, we deliberatelyintroduced base-soluble Zn(II) or Al(III) sites into NiFe layered double hydroxides(LDHs), which are one of the best OER catalysts. Then, the Zn(II) or Al(III) siteswere selectively etched to create atomic M(II)/M(III) defects, which dramaticallyenhanced the OER activity. At a current density of 20 mA·cm^-2, only 200 mV overpotential was required to generate M(II) defect-rich NiFe LDHs, which is the best NiFe-based OER catalyst reported to date. Density functional theory(DFT) calculations revealed that the creation of dangling Ni–Fe sites (i.e., unsaturated coordinated Ni–Fe sites) by defect engineering of a Ni–O–Fe site at the atomic scale efficiently lowers the Gibbs free energy of the oxygen evolutionprocess. This defect engineering strategy provides new insights into catalysts atthe atomic scale and should be beneficial for the design of a variety of catalysts.

Layered double hydroxides (LDHs) have been widely used as catalysts owing to their tunable structure and atomic dispersion of high-valence metal ions; however, limited tunability of electronic structure and valence states have hindered further improvement in their catalytic performance. Herein, we reduced ultrathin LDH precursors in situ and topotactically converted them to atomically thick (~2 nm) two-dimensional (2D) multi-metallic, single crystalline alloy nanosheets with highly tunable metallic compositions. The as-obtained alloy nanosheets not only maintained the vertically aligned ultrathin 2D structure, but also inherited the atomic dispersion of the minor metallic compositions of the LDH precursors, even though the atomic percentage was higher than 20%, which is far beyond the reported percentages for single-atom dispersions (usually less than 0.1%). Besides, surface engineering of the alloy nanosheets can finely tune the surface electronic structure for catalytic applications. Such in situ topotactic conversion strategy has introduced a novel approach for atomically dispersed alloy nanostructures and reinforced the synthetic methodology for ultrathin 2D metal-based catalysts.

Mass production of high-quality silver nanowires (Ag NWs) is of significant importance because of its potential applications in flexible transparent conductive devices. Halogen ions have been widely used for the synthesis of Ag NWs; however, owing to the lack of a deep insight into heterogeneous nucleation processes, usually a trace feeding amount (e.g. [Cl^–] < 0.25 mM) is used, which in turn lowers the concentration of precursor ([Ag⁺]). Here we systematically investigated the nucleation and growth behavior of Ag NWs and concluded that the number of heterogeneous nucleation sites was determined by the total surface area of AgCl seeds, which indicated a linear relationship between the concentrations of Ag⁺ and Cl^– during precipitation. Based on this mechanism, we successfully produced high-quality Ag NWs with Ag⁺ concentrations which were 20 times higher for a polyol system and 5 times higher for an aqueous system as compared to that in the previously reported strategies. Besides, by tailoring the heterogeneous nucleation sites by controlling the size of the AgCl seeds, the diameters of the final Ag NWs could be well controlled even at high Ag⁺ concentration. Based on the mechanistic understandings, this synthetic strategy could be extended to other AgX-seeds (X = Br^–, I^– and SO₄^2–) and the basic principles can be applied to help rational synthesis of other high-yield metal NWs with tunable sizes.

Exploring bifunctional catalysts for the hydrogen and oxygen evolution reactions (HER and OER) with high efficiency, low cost, and easy integration is extremely crucial for future renewable energy systems. Herein, ternary NiCoP nanosheet arrays (NSAs) were fabricated on 3D Ni foam by a facile hydrothermal method followed by phosphorization. These arrays serve as bifunctional alkaline catalysts, exhibiting excellent electrocatalytic performance and good working stability for both the HER and OER. The overpotentials of the NiCoP NSA electrode required to drive a current density of 50 mA/cm² for the HER and OER are as low as 133 and 308 mV, respectively, which is ascribed to excellent intrinsic electrocatalytic activity, fast electron transport, and a unique superaerophobic structure. When NiCoP was integrated as both anodic and cathodic material, the electrolyzer required a potential as low as ~1.77 V to drive a current density of 50 mA/cm² for overall water splitting, which is much smaller than a reported electrolyzer using the same kind of phosphide-based material and is even better than the combination of Pt/C and Ir/C, the best known noble metal-based electrodes. Combining satisfactory working stability and high activity, this NiCoP electrode paves the way for exploring overall water splitting catalysts.