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Electrocatalytic CO2 reduction using metal-free catalysts offers a promising and cost-effective approach to global carbon neutrality. However, metal-free catalysts frequently suffer from unsatisfactory catalytic performances, especially a low current density and poor stability. Herein, by modulating the orbital hybridization state of carbon, we strategically design a regulable sp3 and sp2 hybrid carbon interface embedded with adjacent boron and nitrogen sites in carbon-based metal-free catalysts for CO2 electroreduction. Soft X-ray chemical imaging visually uncovers that the electronic structure and bonding configuration of the boron active site at the hybrid carbon interface are modulated by the neighboring nitrogen site and sp3 carbon. The concomitant electron density reconfiguration around the interface not only delivers optimum upshift of the boron p-band center, and accordingly the moderate valence-electron depletion, to stabilize the *OCHO intermediate favorable for HCOOH generation but also weakens the boron–carbon and boron–hydrogen hybridization of competing *COOH and *H species, respectively, to promote HCOOH selectivity over CO and H2. The designed electrocatalyst realizes a record-high formate partial current density of up to 50.8 mA cm–2 among metal-free catalysts in the H-cell and maintains a high Faradaic efficiency (>90%) over 108 h. This work elevates the carbon interface design with a tailored carbon hybridization state for efficient CO2 electroreduction.

The pursuit of green and sustainable energy is a long-term goal for modern society and people's life. Particularly under the context of carbon neutralization, decarbonization has become a consensus and propels the turning of research enthusiasm to explore new materials and chemistries for energy conversion and storage at a low expenditure. Zinc (Zn) enabled redox flow batteries (RFBs) are competitive candidates to fulfill the requirements of largescale energy storage at the power generation side and customer end. Considering the explosive growth, this review summarizes recent advances in material chemistry for zinc-based RFBs, covering the cathodic redox pairs of metal ions, chalcogens, halogens, and organic molecules. After a brief introduction of common issues for Zn 2+ /Zn conversion reaction at the anode side, the focus is devoted to expounding challenges of redox species and possible problem-solving strategies at the cathode side. Besides, the auxiliary components of separator and current collector are also discussed for achieving optimal RFBs' performance. At last, the conclusion and outlook of future endeavor for Zn-based RFBs implementation are put forward.

δ-MnO2 is a typical oxide with large layered structure for rapid Zn-ion (Zn2+) accommodation capability and widely studied as cathode material in the aqueous Zn-ion batteries (ZIBs). However, structural instability...

Electrochemical energy storage has experienced unprecedented advancements in recent years and extensive discussions and reviews on the progress of multivalent metal-ion batteries have been made mainly from the aspect of electrode materials, but relatively little work comprehensively discusses and provides an outlook on the development of electrolytes in these systems. Under this circumstance, this Review will initially introduce different types of electrolytes in current multivalent metal-ion batteries and explain the basic ion conduction mechanisms, preparation methods, and pros and cons. On this basis, we will discuss in detail the research and development of electrolytes for multivalent metal-ion batteries in recent years, and finally, critical challenges and prospects for the application of electrolytes in multivalent metal-ion batteries will be put forward.