LAUSR

Layered double hydroxide (LDH) nanosheets show good activity in a wide range of photoreactions, with this activity being generally attributable to an abundance of surface oxygen vacancies or coordinatively unsaturated metal cations in the nanosheets which serve as active sites for reactant adsorption and activation. Recently, LDH nanosheets have been shown to be very effective for photocatalytic N2 reduction to NH3 using water as the reducing agent. Herein, it is demonstrated that a simple pretreatment of ZnCr‐LDH, ZnAl‐LDH, and NiAl‐LDH nanosheets with aqueous NaOH can greatly enhance the concentration of oxygen vacancies and low coordination metal centers in the nanosheets, thus significantly enhancing their photocatalytic activity for N2 reduction to NH3 under UV–vis irradiation (without the need for added sacrificial agents or cocatalysts). The facile alkali etching strategy introduced here is expected to be widely adopted in the future development of high‐performance LDH photocatalysts for ammonia production and other challenging chemical transformations (e.g., CO2 reduction and water splitting).