Highly Efficient Photo‐Reduction of p‐Nitrophenol by Protonated Graphitic Carbon Nitride Nanosheets

Abstract

Photocatalytic reduction of p‐nitrophenol to p‐aminophenol is important because of the high toxicity of p‐nitrophenol and the wide application of p‐aminophenol. Graphitic carbon nitride (g‐CN) is an excellent photocatalyst for various photo‐reduction reactions, but inefficient for photo‐reduction of p‐nitrophenol due to the electrostatic exclusion. In this work, we control the morphology and surface property of g‐CN and achieve significantly enhanced activity. The obtained protonated g‐CN nanosheet (pg‐CNNS) material has positively charged surface that can adsorb p‐nitrophenolate anions, therefore facilitating the transfer of photo‐generated electrons from catalyst to p‐nitrophenol. Its reaction rate is 1626 times higher than that of the pristine g‐CN. Besides the surface charge, the morphology of photocatalyst also has important effect on activity, which is demonstrated by the relatively low activity of protonated g‐CN in comparison to pg‐CNNS. The pg‐CNNS photocatalyst has an excellent stability and superior catalytic universality for photo‐reduction of various nitroaromatic compounds. This work does not only expand the application of a well‐known material, but also highlights the importance of understanding photocatalytic mechanism for designing photocatalyst.

New Application and Excellent Performance of Ag/KNbO3 Nanocomposite in Photocatalytic NH3 Synthesis

“…For Ag/KNbO 3 composite it generates a photocurrent of 1.5 μA/cm 2 under visible light, which confirms the existence of the photosensitization effect of Ag NPs. The highest photocurrent is obtained under UV light irradiation, indicating its best efficiency in charge separation. − Meanwhile, it confirms the negative effect of the photosensitization effect. The result in Figure agrees well with the data in Figure , confirming the rationality of the proposed mechanism in Figure .…”

Construction of Hybrid MoS2 Phase Coupled with SiC Heterojunctions with Promoted Photocatalytic Activity for 4-Nitrophenol Degradation

“…In addition, it is obvious that the reaction rate of the 1T/2H-MoS 2 is much higher than the 2H-MoS 2 , that the degradation percentage is 5.4 times that of the 2H-MoS 2 . According to the former research studies, 21,22,33 the 4-NP degradation to 4-AP follows 4 steps, as shown in Figure S3. To confirm the mechanism and further investigate the promotion from the 1T/2H hybrid phase, a series of CV tests were carried out in pH = 6 PBS buffer solution containing 2 mM of 4-NP (Figure 3).…”

“…Comparing with 4-NP, 4-AP could be a useful candidate in analgesic, antipyretic drugs, or corrosion inhibitor fields. 21,22 Light-assisted 4-NP to 4-AP has been reported by various photocatalysts, such as TiO 2 , CdS, etc. 20,23,24 In contrast, the 4-NP can be reduced more easily by catalysts containing noble metallic nanoparticles (such as Au or Ag).…”

“…25−28 However, noble metals are not favored for the industry due to their high cost. Therefore, the coupling system using cheap transition metal oxides/sulfides as alternative catalysts are attractive, like ZrO 2 − TiO 2, 29 Cu 2 O−TiO 2, 30 B,N-doped porous carbon, 31 graphitic carbon nitride, 22 etc. As the release of H 2 from a hole scavenger (usually NaBH 4 , NH 3 BH 3 , or hydrazine, etc.)…”

Graphitic carbon nitride nanoplatelets incorporated titania based type-II heterostructure and its enhanced performance in photoelectrocatalytic water splitting

“…Then, ammonia was added to the above mixture till the pH reached 7 and it was allowed to stir for 30 min. The addition of H 2 SO 4 into g-C 3 N 4 NS helps in exfoliation of nanosheets, by bearing the positive charges and is further neutralized by adding ammonia [33,40]. The final product was centrifuged, washed and dried.…”