Electrochemical nitrate reduction reaction (NO3RR) has recently emerged as an environmentally benign route for sustainable NH3 synthesis under mild conditions. However, the complex 8-electron transfer pathway and various intermediates often lead to sluggish kinetics and limited selectivity. Therefore, the mass transport and conductivity of the electrode play a critical role in the NO3RR process. Herein, NiCoO2 microcubes with different sizes were directly grown on nickel foam (NiCoO2/NF) by regulating the Ni:Co precursor ratio. Increasing cube size induces the formation of three dimensional architecture that facilitates effective electrolyte diffusion within the electrode. Enhanced mass transport was experimentally confirmed by the increased diffusion coefficient determined from electrochemical analysis. Meanwhile, the optimized Ni:Co ratio also modulates the electronic structure of NiCoO2, contributing to improved catalytic activity. Benefiting from these structural and electronic features, the NiCoO2/NF catalyst exhibits outstanding NO3RR activity, achieving an NH3 yield rate of 4133.94 µg h−1 cm−2 and a Faradaic efficiency of 94.56% at −0.1 V vs. RHE. Notably, a remarkable energy efficiency of 39.10% was obtained even at 0 V vs. RHE. This work demonstrates that microcube NiCoO2/NF can serve as highly efficient and durable binder-free electrocatalysts for selective and energy-efficient nitrate reduction toward sustainable NH3 synthesis.

The electrochemical performance of alkaline water electrolyzers is hindered by power fluctuations when integrated with renewable energy sources in terms of electrode degradation. To address this, highly active and durable Fe-incorporated LiNiO2 oxygen evolution reaction (OER) electrodes were fabricated for power-fluctuating operations. The electrodes are synthesized through electrostatic spray deposition (ESD) as a one-step, binder-free, and scalable process. The electronic structure of LiNi1-xFexO2 was tuned by regulating the Ni and Fe content. This analysis suggests that optimal Fe incorporation raises the Ni oxidation state to Ni3+, which likely regulates the eg orbital filling, thereby enhancing OER activity. Density functional theory (DFT) calculations corroborate this electronic modulation and further indicate that the Fe incorporation reduces the theoretical overpotential, consistent with experimental observations. The optimized electrocatalyst, LiNi0.6Fe0.4O2, exhibits remarkable OER performance with an overpotential (246 mV@10 mA cm−2) and a Tafel slope (41 mV dec−1). During half-cell durability tests under various voltage cycling conditions, LiNi0.6Fe0.4O2 exhibits highly stable performance with insignificant degradation, attributed to stable maintenance of Ni3+. Moreover, the alkaline electrolyzer cell test achieved 87.7% voltage efficiency and stable operation for 200 h under power-fluctuating conditions. These results highlight the potential of LiNi0.6Fe0.4O2 for application under variable renewable power supplies.

Although halide perovskite solar cells have achieved remarkable efficiencies close to their theoretical limits, durability against external factors and reproducible processing remain major barriers to commercialization. Conventional ammonium halide-based surface passivation strategies enable effective defect passivation and charge selectivity via 2D/3D heterostructure formation, but their metastability and strong sensitivity to processing conditions limit long-term stability and process window. In this work, we report an amorphous π-conjugated passivator, (4-(3-iodo-9H-carbazol-9-yl)butyl)phosphonic acid (I-4PACz). The asymmetric iodine substituent enhances the molecular dipole moment while simultaneously altering intermolecular interactions, thereby suppressing ordered molecular packing and enabling the formation of a uniform interfacial layer. The characteristics of I-4PACz result in efficient charge extraction as well as widening process window. Perovskite solar modules applied to I-4PACz as passivator between the perovskite and hole transport-layer show a power conversion efficiency of 21.2% with 24.5 cm² aperture size, and excellent long-term stability retaining 85% of the initial efficiency for 884 h under 65°C and 40% relative humidity, and 98.7% of the initial efficiency for 525 h under continuous illumination, respectively. Moreover, the minimal dependence on blade-coating speed also reinforces the suitability of this interfacial control strategy for inline and large-area manufacturing.