Schottky Junctions with Bi Cocatalyst for Taming Aqueous Phase N₂ Reduction toward Enhanced Solar Ammonia Production

Abstract

Solar‐powered N2 reduction in aqueous solution is becoming a research hotspot for ammonia production. Schottky junctions at the metal/semiconductor interface have been effective to build up a one‐way channel for the delivery of photogenerated electrons toward photoredox reactions. However, their applications for enhancing the aqueous phase reduction of N2 to ammonia have been bottlenecked by the difficulty of N2 activation and the competing H2 evolution reaction (HER) at the metal surface. Herein, the application of Bi with low HER activity as a robust cocatalyst for constructing Schottky‐junction photocatalysts toward N2 reduction to ammonia is reported. The introduction of Bi not only boosts the interfacial electron transfer from excited photocatalysts due to the built‐in Schottky‐junction effect at the Bi/semiconductor interface but also synchronously facilitates the on‐site N2 adsorption and activation toward solar ammonia production. The unidirectional charge transfer to the active site of Bi significantly promotes the photocatalytic N2‐to‐ammonia conversion efficiency by 65 times for BiOBr. In addition, utilizing Bi to enhance the photocatalytic ammonia production can be extended to other semiconductor systems. This work is expected to unlock the promise of engineering Schottky junctions toward high‐efficiency solar N2‐to‐ammonia conversion in aqueous phase.

Photoinduced Generation of Metastable Sulfur Vacancies Enhancing the Intrinsic Hydrogen Evolution Behavior of Semiconductors

“…[9][10][11][12] Similar to the biology process, intrasystem electron transfer is the critical step of artificial photosynthesis, which significantly relies on efficient electron relay mediators to couple external electron donors and acceptors. [13][14][15] The difference is that nature carefully selects abundant transition metals (such as nickel and iron) to evolve intrinsic mediators for catalysis, while man-made semiconductorbased catalysts predominantly rely on additional rare precious metals or compounds with platinum-like properties (cocatalyst) to realize electron relay and H─H bond formation. [16][17][18][19] The creation of intrinsic cocatalytic sites over semiconductors is still with great challenges.…”

Recent Progress on Metallic Bismuth‐Based Photocatalysts: Synthesis, Construction, and Application in Water Purification

“…Moreover, the in situ reduction process directly resulted in the porous nanostructure with introduction of Bi. In the study of Huang et al, [ 63 ] Bi nanoparticles were loaded on BiOBr nanoplates by solvothermal method, in which Bi(NO 3 ) 3 and EG were used as precursor and reductant to generate metallic Bi, respectively. In this reaction system, the electrostatic interactions between negatively charged BiOBr and cationic Bi 3+ promoted the nucleation and growth of Bi onto BiOBr.…”

Self-assembled transition metal chalcogenides@CoAl-LDH 2D/2D heterostructures with enhanced photoactivity for hydrogen evolution

“…Photocatalysis using semiconductor materials has been considered as a green approach for hydrogen production. 1 In this realm, a large number of semiconductor materials have been explored, such as metal oxides, 2 metal sulfides, 2,3 Bi-based photocatalysts, 4,5 Ag-based photocatalysts, 6 and g-C 3 N 4 . 7 Of particular note are the transition metal chalcogenides (TMCs: In 2 S 3 , CdS, CdIn 2 S 4 , ZnIn 2 S 4 , etc .…”