Defect and Interface Engineering on Two‐Dimensional Nanosheets for the Photocatalytic Nitrogen Reduction Reaction

Abstract

Reducing dinitrogen (N 2) to ammonia (NH 3) under mild conditions is a very significant nitrogen cyclic process, which plays a vital role in agricultural, biological and industrial fields. The Haber-Bosch process as a current mainstream way of N 2 fixation has particularly high energy consumption, occupying about 1 % of the world energy production. In contrast, the photocatalytic N 2 reduction reaction provides a green route almost without energy consumption and environmental pollution. However, there are many challenges that needs to be solved urgently, such as, for example, low quantum yield, inefficient N 2 adsorption and activation and an unclear N 2 fixation mechanism. Nowadays, tactics for improving the catalytic performance mainly focus on producing more active sites via defect or interface engineering. Generally, two-dimensional materials with defect or interface engineering can not only accelerate photon-exciton interactions, but also enhance sufficient N 2 binding, activation and hydrogenation. In this Minireview, we will first summarize the principles of photocatalytic N 2 fixation, and then discuss progress in the development two-dimensional (2D) materials with defect and interface engineering for photocatalytic N 2 fixation. Finally, we describe ammonia detection methods and recent important developments and challenges in this field.

Recent Progress on Two-Dimensional Materials

“…Recent progress indicated that O, N, and S vacancies exhibited promoting photocatalytic N2 activation on account of their excess electrons and coordinately unsaturated metal sites [1143][1144][1145] . Benefited from high surface atom exposure of 2D materials, anion vacancies could be simply constructed and adjusted on surface by the design of crystal facet, doping and strain [1146][1147][1148] .…”

Metal-free C5N2 doped with a boron atom as an efficient electrocatalyst for the nitrogen reduction reaction

“…In recent years, carbon nitride (CN x ) materials have been considered as promising metal-free catalysts for N 2 reduction due to their excellent activity, high-temperature stability and low cost. [26][27][28][29] It is well known that incorporation of B atoms into CN x can enhance the catalytic activities of CN x materials towards the NRR [30][31][32][33][34][35][36][37] as the electron-deficient B dopants in CN x facilitate the acceptance of lone-pair electrons of N 2 molecules, activating the inert NRN bond and further promoting its cleavage in the subsequent reduction process. For example, Ling et al theoretically proposed that gas phase N 2 can be efficiently reduced to NH 3 on B-decorated C 3 N 4 through the enzymatic mechanism with a record low onset potential (0.20 V).…”

Photocatalytic Nitrogen Reduction by Ti3C2 MXene Derived Oxygen Vacancy‐Rich C/TiO2

“…[ 15 ] Since then, the photocatalytic N 2 fixation becomes highly attractive as a promising strategy for NH 3 synthesis under mild conditions. [ 16–22 ] However, its development is barely satisfactory for the long term in the following decades. [ 23 ] This is due to the difficulty of breaking the highly stable NN triple bond, whose bond energy is as high as 941 kJ mol −1 .…”