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Electrocatalytic CO2reduction is garnering significant interest due to its potential applications in mitigating CO2and producing fuel. However, the scaling up of related catalysis is still hindered by several challenges, including the cost of the catalytic materials, low selectivity, small current densities to maintain desirable selectivity. In this study, Fluorine (F) atoms were introduced into an N-doped carbon-supported single nickel (Ni) atom catalyst via facile polymer-assisted pyrolysis. This method not only maintains the high atom utilization efficiency of Ni in a cost-effective and sustainable manner but also effectively manipulates the electronic structure of the active Ni–N4site through F doping. The catalyst has also been further optimized by controlling the F states, including convalent and semi-ionic states, by adjusting the fluorine sources involved. Consequently, this catalyst with unique structure exhibited comparable electrocatalytic performance for CO2-to-CO conversion, achieving a Faradaic efficiency (FE) of over 99% across a wide potential range and an exceptional CO evolution rate of 9.5 × 104h–1at −1.16 V vs reversible hydrogen electrode (RHE). It also delivered a practical current of 400 mA cm–2while maintaining more than 95% CO FE. Experimental analysis combined with density functional theory (DFT) calculations have also shown that F-doping modifies the electron configuration at the central Ni–N4sites. This modification lowers the energy barrier for CO2activation, thereby facilitating the production of the crucial *COOH intermediate.

Hydrated layered solids are interesting charge storage hosts with potentially high electrochemical activity and interlayer tunability. Although it is often possible to tune their interlayer distance by a pillaring strategy, the poor electrochemical stability of such artificial structures remains a major issue in device operation. Here we investigate the charge storage properties of MOPO4(M = V, Nb) hydrates with a nanosheet morphology to understand the influence of the interlayer environment on cycling stability, as well as ion selectivity. While in hydrated VOPO4interlayer H2O molecules act as compressible springs to enable fast Li-/Na-ion transport kinetics and reasonable structural reversibility, NbOPO4layers with bridging PO4groups serving as permanent linkers exhibit highly stable cyclability for Li-ions, owing to a zero-volume-change ion transport process. However, the latter suffers from a much larger migration energy barrier for Na-ions. Our findings not only highlight a structurally intriguing material system, but also provide insights into reviving materials with an originally unstable interlayer chemical environment, and shed light on the design principles for creating electrochemically stable charge storage hosts.

MoS2holds great promise as a cost-effective alternative to Pt for catalyzing the hydrogen evolution reaction (HER) of water, but its reported catalytic efficiency is still worse than that of Pt, the best HER catalyst but too rare and expensive for mass production of hydrogen. We report a strategy to enable the catalytic activity of monolayer MoS2films that are even better than that of Pt viaengineering the interaction of the monolayer with supporting substrates. The monolayer films were grown with chemical vapor deposition processes and controlled to have an optimal density (7–10%) of sulfur vacancies. We find that the catalytic activity of MoS2can be affected by substrates in two ways: forming an interfacial tunneling barrier with MoS2and modifying the chemical nature of MoS2viacharge transfer (proximity doping). Following this understanding, we enable excellent catalytic activities at the monolayer MoS2films by using substrates that can provide n-doping to MoS2and form low interfacial tunneling barriers with MoS2, such as Ti. The catalytic performance may be further boosted to be even better than Pt by crumpling the films on Ti coated flexible polymer substrates, as the Tafel slope of the film is substantially decreased with the presence of crumpling-induced compressive strain. The monolayer MoS2films show no degradation in catalytic performance after being continuously tested for over 2 months.

Electron-surface scattering is important for many transport phenomena and practical applications. Particularly, the downscaling of microelectronics demands higher electrical conductivity for interconnects, which are currently based on Cu, which suffers from strong surface scattering. However, much is still unclear, such as which surface orientation causes stronger scattering. Existing theories require phenomenological parameters whose values are unknown unless fitted to experimental data or based on assumptions, thereby limiting their accuracy and predictive power. Here we present an accurate, parameter-free approach that enables an accurate calculation of electronic transport with surface scattering. Then we apply it to study the conductivities of Cu films with different surface orientations. Contrary to the common belief that a more compact surface should have higher conductivity, we find that (111) is less conductive than (001). This can be explained by the symmetry of the electronic structure. Furthermore, we propose a phenomenological model that has a better fit to the first-principles results than the conventional one. Our work offers insights into electronic transport and enables accurate calculation, understanding, and prediction for a broad range of systems where surface scattering matters.