A Green Synthesis of Ru Modified g-C ₃ N ₄ Nanosheets for Enhanced Photocatalytic Ammonia Synthesis

Abstract

Nitrate is a crucial environmental pollutant, and its risk on ecosystem keeps increasing. Photocatalytic conversion of nitrate to ammonia can simultaneously achieve the commercialization of environmental hazards and recovery of valuable ammonia, which is green and sustainable for the planet. However, due to the thermodynamic and kinetic energy barriers, photocatalytic nitrate reduction usually involves a higher selectivity of the formation of nitrogen that largely limits the ammonia synthesis activity. In this work, we reported a green and facile synthesis of novel metallic ruthenium particle modified graphitic carbon nitride photocatalysts. Compare with bulk graphitic carbon nitride, the optimal sample had 2.93-fold photocatalytic nitrate reduction to ammonia activity (2.627 mg/h/gcat), and the NH3 selectivity increased from 50.77% to 77.9%. According to the experimental and calculated results, the enhanced photocatalytic performance is attributed to the stronger light absorption, nitrate adsorption, and lower energy barrier for the generation of ammonia. This work may provide a facile way to prepare metal modified photocatalysts to achieve highly efficient nitrate reduction to ammonia.

Boosting Reactive Oxygen Species Generation by Regulating Excitonic Effects in Porphyrinic Covalent Organic Frameworks

“…However, most of the studies about polymeric photocatalysts are related to g-C 3 N 4 or conjugated polymers because of the lack of ordered structures in classical polymers. 18,19 In light of this, covalent organic frameworks (COFs), as a porous crystalline macromolecule with periodic and tailorable structures, can be ideal candidates to investigate excitonic effects by regulating their structures. 20 Previously, a two-dimensional (2D) porphyrinic COF has been proven to own highly efficient photocatalytic activity for molecular oxygen activation with a broad spectral response in the visible light region.…”

“…Therefore, to further improve their photocatalytic performance, developing an advanced method to realize highly efficient dissociation of excitons in polymeric semiconductors is urgently needed. However, most of the studies about polymeric photocatalysts are related to g-C 3 N 4 or conjugated polymers because of the lack of ordered structures in classical polymers. , In light of this, covalent organic frameworks (COFs), as a porous crystalline macromolecule with periodic and tailorable structures, can be ideal candidates to investigate excitonic effects by regulating their structures. − …”

Tailoring the selectivity and activity of oxygen reduction by regulating the coordination environments of carbon-supported atomically dispersed metal sites

“…24,25 In addition, the carbon substrates not only serve as a stabilizing matrix for the C-ADMSs, offering good electron transport, but also inuence the electronic structure of active central sites because of the strong interfacial interactions, which may alter the catalytic performance and contribute to the formation of extra active sites. 21,22,[26][27][28][29] Therefore, the catalytic activity of C-ADMSs is not simply limited by the active central atoms, but the coordination environment between the active metal atoms and surrounding nonmetallic atoms of the support also plays a critical role. [30][31][32][33][34] Lu et al created a series of Pt 1 /NC SACs by varying the coordination number and local composition.…”

Photochemical synthesis of bimetallic CuNiSxquantum dots onto g-C3N4as a cocatalyst for high hydrogen evolution

“…[3][4][5][6] However, various kinds of shortcomings including environmentally pollution, poor visible-light absorption rate, high recombination rate, and chemical instability limit the application of these photocatalysts. [7][8][9] Thus, graphitic carbon nitride (g-C 3 N 4 ), as a 2D novel metal-free polymeric semiconductor photocatalyst, has shown a great development potential owing to its suitable band gap (2.7 eV), low-cost synthesis, thermal stability, environment friendliness, and fascinating planar structure. [10][11][12][13] However, the hydrogen production rate (HER) of pristine g-C 3 N 4 is severely restricted by its low specific surface area, weak absorption, and fast recombination of photogenerated electron-hole pairs.…”