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Uncontrolled mixing remains the primary hurdle impeding the practical application of reverse electrodialysis (RED) to harvest Gibbs free energy in the form of salinity gradients. Improving the permselectivity of membranes is therefore essential, with ionic density being one of the most critical factors. Herein, it is systematically investigated how the charge population in nanofluidic membranes affects the ionic charge separation and consequently the accompanying power density. To establish this relationship, the effect of the ionic density is decoupled from the impact of pore structure using a multivariate strategy to construct covalent‐organic‐framework‐based membranes, in which the content of ionic sites can be precisely manipulated from 0 to 0.18 C m−2, a range that has rarely been experimentally explored. Beyond the region reported (0.002–0.06 C m−2), wherein increasing pore surface charge density of the membrane enhances permselectivity and leads to a greater osmotic voltage, a sharp volcano‐like curve is observed. The optimal membrane affords record‐high power outputs among membrane systems, one order of magnitude higher than the value set for commercialization. The study provides insights into the impact of ionic density of the membrane on osmotic energy harvesting that can guide RED stack design to advance sustainable energy generation from natural salinity gradients. [ABSTRACT FROM AUTHOR]

Nitrogen‐containing compounds, as an important class of chemicals, have been used widely in pharmaceuticals, materials synthesis. Transition metal‐catalyzed reductive amination of an aldehyde or a ketone with ammonia or an amine has been proved to be an efficient and practical method for the preparation of nitrogen‐containing compounds in academia and industry for a century. Given the above, several effective methods using transition metals have been developed in recent years. Noble transition metals like Pd, Pt, and Au‐based catalysts have been predominately used in reductive amination. Because of their high prices, strict official regulations of residues in pharmaceuticals, and deleterious effects on the biological system, their industrial applications are severely hampered. With the increasing sustainable and environmental problems, the Earth‐abundant transition metals including Ti, Fe, Co, Ni, and Zr have also been investigated for the reductive amination reaction and showed great potential to the advancement of sustainable and cost‐effective reductive amination processes. This critical review will mainly summarize the work using Earth‐abundant metals. The effects of different transition metals used in catalytic reduction amination were discussed and compared, and some suggestions were given. The last section highlights the catalytic activities of bi‐ and tri‐metallic catalysts. Indeed, this latter family is very promising and simultaneously benefits from increased stability, and selectivity, compared to monometallic NPs, due to synergistic substrate activation. Few comprehensive reviews focusing on Earth‐abundant transition metals catalyst has been published since 1948, although several authors reported some summaries dealing with one or the other part of this aspect. It is hoped that this critical review will inspire researchers to develop new efficient and selective earth‐abundant metal catalysts for highly, environmentally sustainable reductive amination methods, as well as improve the pharmaceutical industry and related chemical synthesis company traditional method with the utilization of the green method widely. [ABSTRACT FROM AUTHOR]