Aqueous Al-ion batteries (AAIBs) are the subject of great interest due to the inherent safety and high theoretical capacity of aluminum. The high abundancy and easy accessibility of aluminum raw materials further make AAIBs appealing for grid-scale energy storage. However, the passivating oxide film formation and hydrogen side reactions at the aluminum anode as well as limited availability of the cathode lead to low discharge voltage and poor cycling stability. Here, we proposed a new AAIB system consisting of an Al x MnO 2 cathode, a zinc substrate-supported Zn−Al alloy anode, and an Al(OTF) 3 aqueous electrolyte. Through the in situ electrochemical activation of MnO, the cathode was synthesized to incorporate a two-electron reaction, thus enabling its high theoretical capacity. The anode was realized by a simple deposition process of Al 3+ onto Zn foil substrate. The featured alloy interface layer can effectively alleviate the passivation and suppress the dendrite growth, ensuring ultralong-term stable aluminum stripping/ plating. The architected cell delivers a record-high discharge voltage plateau near 1.6 V and specific capacity of 460 mAh g −1 for over 80 cycles. This work provides new opportunities for the development of highperformance and low-cost AAIBs for practical applications.

Herein, the hydrothermal synthesis of porous ultrathin ternary NiFeV layer double hydroxides (LDHs) nanosheets grown on Nickel foam (NF) substrate as a highly efficient electrode toward overall water splitting in alkaline media is reported. The lateral size of the nanosheets is about a few hundreds of nanometers with the thickness of ≈10 nm. Among all molar ratios investigated, the Ni Fe V -LDHs/NF electrode depicts the optimized performance. It displays an excellent catalytic activity with a modest overpotential of 231 mV for the oxygen evolution reaction (OER) and 125 mV for the hydrogen evolution reaction (HER) in 1.0 m KOH electrolyte. Its exceptional activity is further shown in its small Tafel slope of 39.4 and 62.0 mV dec for OER and HER, respectively. More importantly, remarkable durability and stability are also observed. When used for overall water splitting, the Ni Fe V -LDHs/NF electrodes require a voltage of only 1.591 V to reach 10 mA cm in alkaline solution. These outstanding performances are mainly attributed to the synergistic effect of the ternary metal system that boosts the intrinsic catalytic activity and active surface area. This work explores a promising way to achieve the optimal inexpensive Ni-based hydroxide electrocatalyst for overall water splitting.

The oxygen evolution reaction (OER) is a key process involved in energy and environment‐related technologies. An ideal OER electrocatalyst should show high exposure of active sites and optimal adsorption energies of oxygenated species. However, earth‐abundant transition‐metal‐based OER electrocatalysts still operate with sluggish OER kinetics. Here, a cation‐exchange route is reported to fabricate cobalt‐vanadium‐iron (oxy)hydroxide (CoV‐Fe0.28) nanosheets with tunable binding energies for the oxygenated intermediates. The formation of an amorphous/crystalline heterostructure in the CoV‐Fe0.28 catalyst boosts the exposure of active sites compared to their crystalline and amorphous counterparts. Furthermore, the synergetic interaction of Co, V, and Fe cations in the CoV‐Fe0.28 catalyst subtly regulates the local coordination environment and electronic structure, resulting in the optimal thermodynamic barrier for this elementary reaction step. As a result, the CoV‐Fe0.28 catalyst exhibits superior electrocatalytic activity toward the OER. A low overpotential of 215 mV is required to afford a current density of 10 mA cm−2 with a small Tafel slope of 39.1 mV dec−1, which outperforms commercial RuO2 (321 mV and 86.2 mV dec−1, respectively).

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Presented are the development of novel 0D-2D nanohybrids consist of nickel-based bimetal phosphorus trisulfides (Ni 1−x Fe x PS 3 ) nanomosaic that decorated on the surface of MXene nanosheets (denoted as NFPS@MXene). The nanohybrids are obtained through a facile self-assemble process of transition metal layered double hydroxide (TMLDH) on MXene surface; followed by the low temperature in-situ solid-state reaction step. By tuning the Ni:Fe ratio, the as-synthesized NFPS@MXene nanohybrids exhibit excellent activities when tested as electrocatalysts for overall water splitting. Particularly, with the initial Ni:Fe ratio of 7:3, the obtained Ni 0.7 Fe 0.3 PS 3 @MXene nanohybrid reveals low overpotential (282 mV) and Tafel slope (36.5 mV dec -1 ) for oxygen evolution reaction (OER) in 1 m KOH solution. Meanwhile, the Ni 0.9 Fe 0.1 PS 3 @MXene shows low overpotential (196 mV) for hydrogen evolution reaction (HER) in 1 m KOH solution. When integrated them for overall water splitting, the Ni 0.7 Fe 0.3 PS 3 @MXene || Ni 0.9 Fe 0.1 PS 3 @MXene couple shows a low onset potential of 1.42 V and needs only 1.65 V to reach a current density of 10 mA cm -2 , which is better than the all noble metal IrO 2 || Pt/C electrocatalyst (1.71 mV@10 mA cm −2 ). Given the chemical versatility of Ni 1−x Fe x PS 3 and the convenient self-assemble process, the nanohybrids demonstrated in this work are promising for energy conversion applications.