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Sodium-ion battery (SIB) is an ideal candidate for large-scale energy storage due to high abundant sodium sources, relatively high energy density, and potentially low costs. Hard carbons, as one of the most promising anodes, could deliver high plateau capacities at low potentials, which boosts the energy densities of SIBs. Their slope capacities have been demonstrated from the defect adsorption of sodium ions, while the plateau capacity depends highly on intercalation and pore filling. Nevertheless, the specific structures of sodium ions stored in hard carbons have not been clarified, namely active sites of adsorption, intercalation, and pore-filling mechanisms. Therefore, delicate synthesis methods are required to prepare hard carbons with controllable specific structures, along with elucidating the precise active sites for enhancing the Na-ion storage performance. To offer databases for future designs, we summarized the synthesis strategies of hard carbon anodes for constructing active sites of plateau capacities. Synthesis methods were highlighted with corresponding influences on the meticulous structures of hard carbons and Na-ion storage behaviors. Last but not least, perspectives were proposed for developing hard carbon anodes from the points of research and practical applications.

Electrocatalytic hydrogenation (ECH) of organics using water as hydrogen donors has been regarded as a green organic reduction technique to replace traditional chemical reactions that use sacrificial chemicals. The development of ECH process provides potential applications in the production of value-added chemicals owing to its low energy consumption, low pollution, high safety, and superior sustainability. However, its application is limited by the low conversion rate and poor selectivity toward desired products. The efficiency of ECH can be improved by rational design of electrocatalysts. This review covers several representative electrocatalytic systems (aldehydes, ketones, phenolic organics, alkynes, and organonitrogen compounds) and summarizes different ECH mechanisms, followed by thorough discussion on the modification strategies of electrocatalysts that are currently adopted to enhance the catalytic performance. Finally, in view of the current challenges for ECH, we discuss possible future directions in the field, aiming to provide guidance to the catalyst design toward highly efficient ECH reactions over different organic feedstocks.