Aqueous Zn-ion batteries (AZIBs), being safe, inexpensive, and pollution-free, are a promising candidate for future large-scale sustainable energy storage. However, in a conventional AZIBs setup, the Zn metal anode suffers oxidative corrosion, side reactions with electrolytes, disordered dendrite growth during operation, and consequently low efficiency and short lifespan. In this work, we discover that purging CO2 gas into the electrolyte could address these issues by eliminating dissolved O2, inhibiting side reactions by buffering the local pH change, and preventing dendrite growth by inducing the in situ formation of a ZnCO3 solid electrolyte interphase layer. Moreover, the CO2-purged electrolyte could enable a highly reversible plating/stripping behavior with a high Coulombic efficiency of 99.97% and an ultralong lifespan of 32,000 cycles (1600 h) even under an ultrahigh current density of 40 mA cm–2. Consequently, the CO2-purged symmetrical cells deliver long cycling stability at a high depth of discharge of 57%, while the CO2-purged Zn/V2O5 full cells exhibit outstanding capacity retention of 66% after 1000 cycles at a high current density of 5 A g–1. Our strategy, the simple introduction of CO2 gas into the electrolyte, could effectively mediate the zinc anode’s critical issues and provide a scalable and cost-effective pathway for the commercialization of AZIBs.

Semiconductor‐based photocatalytic solar‐to‐fuel conversion has proven an appealing strategy for achieving carbon‐neutral and green‐hydrogen production. However, almost all semiconductors exhibit unsatisfactory photocatalytic performance due to insufficient surface‐active sites, weak selectivity, and fast charge‐carrier recombination. For these reasons, cocatalyst loading has become an encouraging strategy for improving photocatalytic activity and selectivity. Owing to the scarcity, and cost of noble metal‐based cocatalysts, utilization of low‐cost noble‐metal‐free cocatalysts, such as metal carbide‐based cocatalysts, has aroused tremendous attention. This review highlights some recent crucial advances in active metal carbide‐based cocatalysts for photocatalytic solar‐to‐fuel conversion. First, the fundamentals of metal carbide‐based cocatalysts are presented, including the photocatalytic mechanism, advantages, drawbacks, and design rules. Second, three synthesis approaches of high‐active metal carbide‐based cocatalysts, namely constructing metal carbide nanostructures, epitaxial synthesis of metal carbides on nanostructured carbon, and crystal imperfection construction on metal carbides, are thoroughly addressed. Subsequently, applications of metal carbide‐based cocatalysts in photocatalytic hydrogen production, CO2 reduction, and nitrogen reduction are further discussed. Finally, the crucial challenges and important directions of metal carbide‐based cocatalysts for photocatalytic solar‐to‐fuel conversion are proposed. This review demonstrates some new options for rationally designing and developing novel and efficient metal carbide‐based cocatalysts for highly active and selective photocatalytic solar‐to‐fuel conversion.

One of the most unique properties of two‐dimensional carbides and nitrides of transition metals (MXenes) is their excellent water dispersibility and yet possessing superior electrical conductivity but their industrial‐scale application is limited by their costly chemical synthesis methods. In this work, the niche feature of MXenes was capitalized in the packed‐bed electrochemical reactor to produce MXenes at an unprecedented reaction rate and yield with minimal chemical waste. A simple NH4F solution was employed as the green electrolyte, which could be used repeatedly without any loss in its efficacy. Surprisingly, both fluoride and ammonium were found to play critical roles in the electrochemical etching, functionalization, and expansion of the layered parent materials (MAXs) through which the liberation of ammonia gas was observed. The electrochemically produced MXenes with excellent conductivity, applied as supercapacitor electrodes, could deliver an ultrahigh volumetric capacity (1408 F cm−3) and a volumetric energy density (75.8 Wh L−1). This revolutionary green, energy‐efficient, and scalable electrochemical route will not only pave the way for industrial‐scale production of MXenes but also open up a myriad of versatile electrochemical modifications for improved functional MXenes.

Lithium‐sulfur (Li‐S) batteries have been regarded as promising next‐generation energy storage systems due to their high energy density and low cost, but their practical application is hindered by inferior long‐cycle stability caused by the severe shuttle effect of lithium polysulfides (LiPSs) and sluggish reaction kinetics. This study reports a La2O3‐MXene heterostructure embedded in carbon nanofiber (CNF) (denoted as La2O3‐MXene@CNF) as a sulfur (S) host to address the above issues. The unique features of this heterostructure endow the sulfur host with synergistic catalysis during the charging and discharging processes. The strong adsorption ability provided by the La2O3 domain can capture sufficient LiPSs for the subsequent catalytic conversion, and the insoluble thiosulfate intermediate produced by hydroxyl terminal groups on the surface of MXene greatly promotes the rapid conversion of LiPSs to Li2S via a “Wackenroder reaction.” Therefore, the S cathode with La2O3‐MXene@CNF (La2O3‐MXene@CNF/S) exhibits excellent cycling stability with a low capacity fading rate of 0.031% over 1000 cycles and a high capacity of 857.9 mAh g−1 under extremely high sulfur loadings. Furthermore, a 5 Ah‐level pouch cell is successfully assembled for stable cycling, which delivers a high specific energy of 341.6 Wh kg−1 with a low electrolyte/sulfur ratio (E/S ratio).