The transport of fluids in channels with diameter of 1-2 nm exhibits many anomalous features due to the interplay of several genuinely interfacial effects. Quasi-unidirectional ion transport, reminiscent of the behavior of membrane pores in biological cells, is one phenomenon that has attracted a lot of attention in recent years, e.g., for realizing diodes for ion-conduction based electronics. Although ion rectification has been demonstrated in many asymmetric artificial nanopores, it always fails in the high-concentration range, and operates in either acidic or alkaline electrolytes but never over the whole pH range. Here we report a hierarchical pore architecture carbon membrane with a pore size gradient from 60 nm to 1.4 nm, which enables high ionic rectification ratios up to 10⁴ in different environments including high concentration neutral (3 M KCl), acidic (1 M HCl), and alkaline (1 M NaOH) electrolytes, resulting from the asymmetric energy barriers for ions transport in two directions. Additionally, light irradiation as an external energy source can reduce the energy barriers to promote ions transport bidirectionally. The anomalous ion transport together with the robust nanoporous carbon structure may find applications in membrane filtration, water desalination, and fuel cell membranes.

The Oxygen and nitrogen plasma treatment were applied to produce graphene with abundant edges, oxygen functional groups, and nitrogen doping. The plasma-etched graphene was then used as a metal-free electrocatalyst in a solid acid fuel cell. Scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the graphene layers. Alternating-current impedance spectroscopy of a hybrid electrode containing the plasma-etched graphene and cesium dihydrogen phosphate as proton-conducting solid acid illustrated its remarkable catalytic activity under cathodic conditions. Thus, both O₂ and N₂ plasma treatment activated the material. While O₂ plasma was a more effective activator than N₂ plasma, it also resulted in higher degradation rates. A combination of density functional theory calculations and experimental results indicated that zigzag carbon was the most active site for the oxygen reduction reaction on both O₂ and N₂ plasma-etched graphene. Furthermore, the armchair carbons adjacent to the surface oxygen groups and doped heteroatoms were also important active sites for O₂ and N₂ plasma-etched graphene, respectively. The results of this study will guide future endeavors in the development of non-precious metal catalysts for use as fuel cell cathodes.

Electrocatalytic water splitting offers a promising route to sustainable H₂, but the oxygen evolution reaction (OER) in alkaline media remains the principal bottleneck for activity and durability. This review focuses on alkaline OER and integrates mechanism, kinetics, materials design, and cell-level considerations. Reaction mechanisms are outlined, including the adsorbate evolution mechanism (AEM) and the lattice oxygen mediated mechanism (LOM), together with universal scaling constraints and operando reconstruction of precatalysts into active oxyhydroxides. Strategies for electronic tuning, defect creation, and heterointerface design are linked to measurable kinetics, including iR-corrected overpotential, Tafel slope, charge transfer resistance, and electrochemically active surface area (ECSA). Representative catalyst families are critically evaluated, covering Ir and Ru oxides, Ni-, Fe-, and Co-based compounds, carbon-based materials, and heterostructure systems. Electrolyte engineering is discussed, including control of Fe impurities and cation and anion effects, and gas management at current densities of 100–500 mA·cm⁻² and higher. Finally, we outline challenges and directions that include operando discrimination between mechanisms and possible crossover between AEM and LOM, strategies to relax scaling relations using dual sites and interfacial water control, and constant potential modeling with explicit solvation and electric fields to enable efficient, scalable alkaline electrolyzers.

The stability of electrocatalysts grown on substrates is a significant challenge for the construction of 3‐dimensional (3D) stainless‐steel (SS)‐based electrodes for highly efficient water splitting. This paper presents an efficient and universal process to enhance the interfacial interaction between SS and highly active electrocatalysts for the preparation of 3D electrodes through the formation of an interfacial network of carbon nanotubes (CNTs) on the SS. Nanoscale X‐ray computed tomography and focused ion beam are used to visualize the interface between CNTs and SS, and 3D structure of CNT/SS electrodes. The strongly interconnected CNTs network increases the surface area of the SS support that benefits the modification of highly active electrocatalysts and also serves as an electron/charge‐conductive highway between electrocatalysts and support. The electrocatalysts on CNT/SS further improve hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) performances, respectively, of the 3D electrodes. While compared to the SS‐based electrodes reported recently, Pt/OxCNT/SS shows the best HER activity over wide pH range and RuO₂/OxCNT/SS exhibits a comparable OER performance in neutral and alkaline electrolyte. An efficient approach is reported to combine highly active electrocatalysts with SS for the preparation of active and stable 3D electrodes that can be further explored in various areas.