The pH monitoring is significantly important in chemical industry, biological process, and pollution treatment. However, it remains a great challenge to measure pH in extreme alkalinity conditions. Herein, we employ an electrolyte-gated field-effect-transistor (FET) strategy using non-stoichiometric SrCoO_x with rich oxygen-vacancy defects as channel materials for detecting extreme alkalinity. The corresponding channel can provide effective oxygen-ion-migration sites for reversible transformation of OH⁻ ↔ O²⁻ + H⁺ driven by electric field. The resultant electrolyte-gated FET sensor exhibits a sensitive linear response to high concentrations of alkaline solution, 1–20 M. Significantly, the sensor has the ability to directly indicate the pH values ranging from 14.0 to 17.0 in consideration of ion-activity coefficient data. This work offers a great possibility for directly detecting base concentration as well as pH values in extreme alkaline solutions.

As an ideal carbon-free energy carrier, ammonia plays an indispensable role in modern society. The conventional industrial synthesis of NH₃ by the Haber–Bosch technique under harsh reaction conditions results in serious energy consumption and environmental pollution. Therefore, it is essential to develop NH₃ synthesis tactics under benign conditions. Electrochemical synthesis of NH₃ has the advantages of mild reaction conditions and environmental friendliness, and has become a hotspot for research in recent years. It has been reported that zinc-nitrogen batteries (ZNBs), such as Zn-N₂, Zn-NO, Zn-NO₃⁻, and Zn-NO₂⁻ batteries, can not only reduce nitrogenous species to ammonia but also have concomitant power output. However, the common drawbacks of these battery systems are unsatisfactory power density and ammonia production. In this review, the latest progress of ZNBs including the reaction mechanism of the battery and reactor design principles is systematically summarized. Subsequently, active site engineering of cathode catalysts is discussed, including vacancy defects, chemical doping, and heterostructure engineering. Finally, some insights are provided to improve the performance of ZNBs from a practical perspective of view.