A Schottky‐Barrier‐Free Plasmonic Semiconductor Photocatalyst for Nitrogen Fixation in a “One‐Stone‐Two‐Birds” Manner

Plasmonic photocatalysis has received much attention owing to attractive plasmonic enhancement effects in improving the solar-to-chemical conversion efficiency. However, the photocatalytic efficiencies have remained low mainly due to the short carrier lifetime caused by the rapid recombination of plasmon-generated hot charge carriers. Although plasmonic metal-semiconductor heterostructures can improve the separation of hot charge carriers, a large portion of the hot charge carriers are lost when they cross the Schottky barrier. Herein, a Schottky-barrier-free plasmonic semiconductor photocatalyst, MoO3- x , which allows for efficient N2 photofixation in a "one-stone-two-birds" manner, is demonstrated. The oxygen vacancies in MoO3- x serve as the "stone." They "kill two birds" by functioning as the active sites for the chemisorption of N2 molecules and inducing localized surface plasmon resonance for the generation of hot charge carriers. Benefiting from this unique strategy, plasmonic MoO3- x exhibits a remarkable photoreactivity for NH3 production up to the wavelength of 1064 nm with apparent quantum efficiencies over 1%, and a solar-to-ammonia conversion efficiency of 0.057% without any hole scavenger. This work shows the great potential of plasmonic semiconductors to be directly used for photocatalysis. The concept of the Schottky-barrier-free design will pave a new path for the rational design of efficient photocatalysts.