The large-scale decommissioning of lithium-ion batteries (LIBs) production is progressing rapidly, and the demand for environmentally friendly recycling and material recovery is rising. Collectively, this review has presented a series of studies on recent progress in using waste LIB black mass to synthesize various materials for water treatment, including synthesis methods, material structure and application performance of derived adsorbents, Fenton catalysts, persulfate-activating catalysts, etc. The above are based on rational material design and processing to create high-efficiency, multi-functional water treatment materials from black mass. Anode graphite-based adsorbents are a typical representative type with good heavy metal adsorption performance, and cathode-derived catalysts show fast degradation of organic pollutants via oxidative pathways. This review briefly introduces the shortcomings of the current state and provides some directions for further research to promote the construction of an effective pollution treatment model in the circular economy era.

Developing efficient electrocatalysts towards water oxidation is of critical importance for numerous environmental and energy technologies. Single-atom catalysts have been widely recognized as a promising route, they are however often anchored on semiconducting substrates such as hydroxides, which inherently limits the electrical conductivity and overall catalytic efficiency. In this work, single-atom Ru catalysts are immobilized on a semi-metallic layered double hydroxide substrate (Ru-SM LDH) to achieve highly efficient water oxidation. The as-designed Ru-SM LDH catalyst displayed an overpotential of 270 mV to deliver an oxygen evolution reaction (OER) current density of 100 mA cm⁻², which was 60 mV lower than that of commercial RuO₂. In-situ electrochemical impedance spectroscopy revealed that Ru-SM LDH exhibited a reduced solution resistance and diminished charge transfer resistance during catalysis, leading to the enhanced OER performance. An electrolyzer assembled with Ru-SM LDH anode and commercial Ni mesh cathode achieved a water electrolysis current density of 400 mA cm⁻² at 1.65 V and demonstrated exceptional stability for 1000 h, surpassing that of Ni||Ni electrolyzer (1.92 V, 350 h). These findings established the design of single-atom catalysts supported on semi-metallic hydroxide substrates as a robust pathway toward efficient water electrolysis catalysts.

The development of efficient electrocatalysts for saline water oxidation (SWO) is imperative for advancing seawater splitting technology to produce green hydrogen. In this work, we report a NiFeCo hydroxychloride pre-electrocatalyst with the merits of high surface area and anti-corrosion, which exhibited both active and stable SWO performance. The lattice Cl⁻ of NiFeCo hydroxychloride was leached during catalysis, leading to the 35.4% enlarged surface area of the catalysts, which showed a SWO overpotential of 369 mV at 100 mA·cm⁻², which is 105 and 154 mV lower than that of the NiFeCo layered double hydroxide and commercial RuO₂ catalysts, respectively. Moreover, in-situ Raman demonstrated the incorporation of electrolyte Cl⁻ to the lattice of the catalysts and the re-formation of Co–Cl bonds, which resulted in the enhanced anti-corrosion performance and high electrocatalytic stability for 100 h. These results provide a convincing demonstration of the reconstruction of ternary hydroxychloride pre-electrocatalysts for efficient seawater splitting hydrogen production.

Aqueous Zn batteries are promising candidates for grid-scale renewable energy storage. Foil electrodes have been widely investigated and applied as anode materials for aqueous Zn batteries, however, they suffer from limited surface area and severe interfacial issues including metallic dendrites and corrosion side reactions, limiting the depth of discharge (DOD) of the foil electrode materials. Herein, a low-temperature replacement reaction is utilized to in-situ construct a three-dimensional (3D) corrosion-resistant interface for deeply rechargeable Zn foil electrodes. Specifically, the deliberate low-temperature environment controlled the replacement rate between polycrystalline Zn metal and oxalic acid, producing a Zn foil electrode with distinct 3D corrosion-resistant interface (3DCI-Zn), which differed from conventional two-dimensional (2D) protective structure and showed an order of magnitude higher surface area. Consequently, the 3DCI-Zn electrode exhibited dendrite-free and anti-corrosion properties, and achieved stable plating/stripping performance for 1000 ​h at 10 ​mA ​cm⁻² and 10 mAh cm⁻² with a remarkable DOD of 79 ​%. After pairing with a MnO₂ cathode with a high areal capacity of 4.2 mAh cm⁻², the pouch cells delivered 168 ​Wh L⁻¹ and a capacity retention of 89.7 % after 100 cycles with a low negative/positive (N/P) ratio of 3:1.