Exploration of high‐performance cathode materials for rechargeable aqueous Zn ion batteries (ZIBs) is highly desirable. The potential of molybdenum trioxide (MoO 3 ) in other electrochemical energy storage devices has been revealed but held understudied in ZIBs. Herein, a demonstration of orthorhombic MoO 3 as an ultrahigh‐capacity cathode material in ZIBs is presented. The energy storage mechanism of the MoO 3 nanowires based on Zn 2+ intercalation/deintercalation and its electrochemical instability mechanism are particularly investigated and elucidated. The severe capacity decay of the MoO 3 nanowires during charging/discharging cycles arises from the dissolution and the structural collapse of MoO 3 in aqueous electrolyte. To this end, an effective strategy to stabilize MoO 3 nanowires by using a quasi‐solid‐state poly(vinyl alcohol)(PVA)/ZnCl 2 gel electrolyte to replace the aqueous electrolyte is developed. The capacity retention of the assembled ZIBs after 400 charge/discharge cycles at 6.0 A g −1 is significantly boosted, from 27.1% (in aqueous electrolyte) to 70.4% (in gel electrolyte). More remarkably, the stabilized quasi‐solid‐state ZIBs achieve an attracting areal capacity of 2.65 mAh cm −2 and a gravimetric capacity of 241.3 mAh g −1 at 0.4 A g −1 , outperforming most of recently reported ZIBs.

CsPbI3 inorganic perovskite has exhibited some special properties particularly crystal structure distortion and quantum confinement effect, yet the poor phase stability of CsPbI3 severely hinders its applications. Herein, the nature of the photoactive CsPbI3 phase transition from the perspective of PbI6 octahedra is revealed. A facile method is also developed to stabilize the photoactive phase and to reduce the defect density of CsPbI3. CsPbI3 is decorated with multifunctional 4‐aminobenzoic acid (ABA), and steric neostigmine bromide (NGBr) is subsequently used to further mediate the thin films' surface (NGBr‐CsPbI3(ABA)). The ABA or NG cation adsorbed onto the grain boundaries/surface of CsPbI3 anchors the PbI6 octahedra via increasing the energy barriers of octahedral rotation, which maintains the continuous array of corner‐sharing PbI6 octahedra and kinetically stabilizes the photoactive phase CsPbI3. Moreover, the added ABA and NGBr not only interact with shallow‐ or deep‐level defects in CsPbI3 to significantly reduce defect density, but also lead to improved energy‐level alignment at the interfaces between the CsPbI3 and the charge transport layers. Finally, the champion NGBr‐CsPbI3(ABA)‐based inorganic perovskite solar cell delivers 18.27% efficiency with excellent stability. Overall, this work demonstrates a promising concept to achieve highly phase‐stabilized inorganic perovskite with suppressed defect density for promoting its optoelectronic applications.

A new solar-microbial hybrid device based on oxygen-deficient Nb2O5 anodes for sustainable hydrogen generation without external bias was demonstrated.