Fe-Doped BiOCl Nanosheets with Light-Switchable Oxygen Vacancies for Photocatalytic Nitrogen Fixation

Abstract

Since photocatalytic N2 to NH3 is a kinetically complex and multielectron reaction, designing efficient materials to fix N2 is highly essential. Herein, we reported that simultaneously introducing oxygen vacancy and doping Fe into BiOCl nanosheets (NSs) can greatly boost the photocatalytic N2 fixation. BiOCl NSs-Fe-5% exhibit the maximum NH3 generation rate of 1.022 mmol g–1 h–1 and durable stability after successive cycling, being one of the best photocatalysts for N2 fixation. This work demonstrates a promising strategy to design efficient photocatalysts for N2 fixation, holding great significance for extensions to other material systems.

Progress and challenges in photocatalytic ammonia synthesis

“…In another related work by incorporating Fe into BiOCl nanosheets, Fe-doped BiOCl nanosheets (BiOCl NSs-Fe) were developed for N2 photoreduction. 66 The optimal BiOCl NSs-Fe exhibited a marked enhancement of photocatalytic NH3 production, and the efficiency was 2.53 times higher than that of pristine BiOCl NSs. In another study, Mo was successfully doped into the W18O49 nanowires to produce the Mo-doped W18O49 nanowires (MWO-1) as shown in Fig.…”

“…The surface regulations, including defect engineering and morphology engineering, significantly determine the photocatalytic activity because they can promote the surface adsorption and activation of N2. 23,[31][32][33][34][35][36][37][38][39][40][54][55][56][57][64][65][66][67][68][69][70][71] The interface modulations, including the modification with cocatalysts and semiconductors, greatly affect the charge transfer and separation efficiency. [89][90][91][92][93][94][95][96][97][98][99][100][101][109][110][111] We will discuss these factors one by one below.…”

Fundamentals and Recent Progress of Photocatalytic Nitrogen‐Fixation Reaction over Semiconductors

“…AQE is a convenient and widely used performance parameter of the photocatalytic nitrogen‐fixation systems. [ 11,13,30,43–45 ] It can be expressed as the product of light absorption, charge separation, and surface redox reaction efficiency, and is usually calculated based on the number of incident photons per unit area but not the actual number of photons absorbed by the photoreaction system as the light reflection and transmission losses are not considered. In addition, AQE reflects the energy conversion efficiency of photocatalysts at a specific monochromatic light wavelength, and thus special attention should be paid to the spectral purity of monochromatic light, the measurement accuracies of photon number and irradiation area when measuring the AQE of nitrogen‐fixation system.…”

“…Hitherto, many efforts have been made on the choice and modification of semiconductors, such as doping, introducing vacancy, supporting cocatalyst, morphology regulation, and constructing heterojunction, to accelerate the nitrogen‐fixation processes. Based on the elemental compositions, the various nitrogen‐fixation photocatalysts can be will be classified into the following categories: TiO 2 and other metal oxides, [ 30–32,52–54,83–91,96–99,103,104 ] bismuth oxyhalides, [ 41–45,105–111 ] metal sulfides and biomimetic materials, [ 12–14,36,37,112–116 ] graphitic nitride carbon, [ 99,117–123 ] and the relative composites or heterojunctions. [ 55,62,78,88,99,114,121–124 ] In the subsequent sections, the photocatalysts will be classified based on their elemental compositions and nitrogen‐fixation reactions (NRR and NOR).…”

“…In 1977, Schrauzer and Guth first reported that N 2 can be photocatalytically reduced to NH 3 and N 2 H 4 over TiO 2 , and Fe 2 O 3 loading can improve the nitrogen‐fixation ability of TiO 2 . [ 27 ] Since then, various semiconducting materials, such as oxides, [ 11,28–35 ] sulfides, [ 12–14,36,37 ] hydroxides, [ 38–40 ] and bismuth halides, [ 41–45 ] have been used as the nitrogen‐fixation photocatalysts. Also, many strategies including manufacturing defects, supporting cocatalysts, and constructing heterojunctions have been developed to improve the nitrogen‐fixation performance.…”