Single-Atom Pt–N₃ Sites on the Stable Covalent Triazine Framework Nanosheets for Photocatalytic N₂ Fixation

Abstract

The commercial Haber-Bosch process for NH3 production not only requires large amounts of energy and hydrogen supply but also generates tremendous greenhouse CO2 emission. To mitigate energy and environmental challenges, renewable ammonia production technologies based on electrochemical and photochemical methods, in particular, photocatalytic nitrogen fixation in aqueous phase for ammonia production is highly desired. In the present work, single-atom Pt anchored at the −N3 sites of stable and ultrathin covalent triazine framework (CTF) nanosheets have been successfully synthesized (Pt-SACs/CTF). The well-defined coordination structure of Pt–N3 sites in the Pt-SACs/CTF catalyst have been characterized using HAADF-STEM and EXAFS, as well as ab initio molecular dynamics simulations. The ammonia production rate over the as-synthesized Pt-SACs/CTF catalyst is 171.40 μmol g–1 h–1 in the absence of sacrificial agent. On the basis of density functional theory calculations, it has been found that the alternating mechanism is energetically more favorable than the distal mechanism over the well-defined Pt–N3 sites. The significance of the present work is to demonstrate that the single-atom metal catalysts are anchored at the two-dimensional stable CTF nanosheets for photocatalytic nitrogen fixation to ammonia.

Vacancy Engineering in Semiconductor Photocatalysts: Implications in Hydrogen Evolution and Nitrogen Fixation Applications

“…[ 11 ] The production of green H 2 is of great importance to lower the energy consumption and environmental damage by the current industrial processes like steam‐reforming of methane. [ 12 ] As the storage of H 2 is trickier, ammonia (NH 3 ) has been recognized as a potential option for H 2 storage due to its high hydrogen content and is the backbone of fertilizer industries. Currently, NH 3 is prepared by the Bosch–Haber process, which is not very economical and consumes a huge amount of energy due to its harsh reaction requirements.…”

Progress and challenges in photocatalytic ammonia synthesis

“…Recently, single-atom Pt modified triazine framework (CTF) nanosheets (Pt-SACs/CTF) was developed for the photocatalytic NH3 production. 108 It was found that the Pt-N3 sites were formed in Pt-SACs/CTF, leading to more negative conduction band position with accelerated thermodynamics and fast interfacial charge migration ability, and therefore a high NH3 production rate of 171.4 µmol g -1 h -1 under visible light irradiation. Most recently, we synthesized a ternary Ru/RuO2/g-C3N4 system for N2 photoreduction, which exhibited the photocatalytic NH3 yield of 13.3 µmol g -1 h -1 whilst no NH3 could be measured for pure g-C3N4 under the same condition.…”

MXenes as Superexcellent Support for Confining Single Atom: Properties, Synthesis, and Electrocatalytic Applications

“…are utilized as supports to anchor single metal atom. [16][17][18][19] Among them, 2D nanomaterials are regarded as superexcellent supports due to the ultrabroad specific surface area, and unrivaled geometric and electronic structures. [20][21][22] As a recently discovered 2D layered nanomaterials, MXenes with analogous graphene structure represent the transition metal carbides, nitrides, and carbonitride.…”