Solar-Powered Photodegradation of Pollutant Dyes Using Silver-Embedded Porous TiO2 Nanofibers

Titanium dioxide (TiO2) nanomaterials have been ubiquitously investigated as a photocatalyst for organic contaminant treatment in wastewater due to their exemplary semiconductor properties. However, their huge band gap remains a barrier for visible light absorption, limiting their utility in practical applications. The incorporation of noble metals in the TiO2 scaffold would help mitigate the problem via plasmonic resonance enhancements. Silver (Ag) is the chosen noble metal as it is relatively cheap and has great plasmonic effects. In this study, the use of electrospun Ag-embedded TiO2 nanofibers as a photocatalyst is shown to be effective in decomposing rhodamine B and methyl orange dyes under a solar simulator in 3 h, which is more efficacious as opposed to pristine TiO2 nanofibers. This showcases the potential of a simple and economic wastewater treatment system for the removal of organic pollutants

Photocatalytic deconstructive aliphatic carbon–carbon bond cleavage and functionalization of unactivated alcohols

Carbon–carbon (C–C) bonds are challenging to selectively cleave owing to their chemical inertness and omnipresence in organic molecules; however, they can be targeted during the late-stage modification of natural products and active pharmaceutical ingredients. Herein, we report a selective deconstructive C(sp3)–C(sp3) bond cleavage and difunctionalization of unactivated alcohols mediated by a vanadium visible-light photocatalyst under ambient temperatures and pressures. Our base metal photocatalyst operates via ligand-to-metal charge transfer followed by an inner-sphere C–C bond cleavage to generate alkyl radicals that are trapped with SOMOphiles. We achieved 10 different bond formations on 44 examples using a range of commercially sourced alcohols, including natural products and biomolecules. Our protocol can also be used for the regio- and diastereoselective cyclization to form an α-aminolactone, and for the late-stage functionalization of bioactive oligopeptides to access unnatural amino acid residues.Agency for Science, Technology and Research (A*STAR)Ministry of Education (MOE)Nanyang Technological UniversityPublished versionH.S.S. acknowledges that this project is supported by A*STAR under the AME IRG grants A2083c0050 and A1783c0002. H.S.S. is also grateful for the Singapore Ministry of Education Academic Research Fund Tier 1 grants RT 05/19 and RG 09/22. We thank NTU for the fifth ACE Grant. Acknowledgment is made to the American Chemical Society Green Chemistry Institute Pharmaceutical Roundtable Research Grant for partial support of this research. B.R. thanks A*STAR, Singapore for funding under the Accelerated Materials Development for Manufacturing Program (grant no. A1898b0043). X.-W.L. acknowledges that this project is supported by A*STAR under the AME IRG grant A20E5c0087 and also thanks the Singapore Ministry of Education for funding the Academic Research Fund Tier 1 grant RG 09/20.c

Integration of single-atom catalyst with Z-scheme heterojunction for cascade charge transfer enabling highly efficient piezo-photocatalysis

Piezo-assisted photocatalysis (namely, piezo-photocatalysis), which utilizes mechanical energy to modulate spatial and energy distribution of photogenerated charge carriers, presents a promising strategy for molecule activation and reactive oxygen species (ROS) generation toward applications such as environmental remediation. However, similarly to photocatalysis, piezo-photocatalysis also suffers from inferior charge separation and utilization efficiency. Herein, a Z-scheme heterojunction composed of single Ag atoms-anchored polymeric carbon nitride (Ag-PCN) and SnO2- x is developed for efficient charge carrier transfer/separation both within the catalyst and between the catalyst and surface oxygen molecules (O2 ). As revealed by charge dynamics analysis and theoretical simulations, the synergy between the single Ag atoms and the Z-scheme heterojunction initiates a cascade electron transfer from SnO2- x to Ag-PCN and then to O2 adsorbed on Ag. With ultrasound irradiation, the polarization field generated within the piezoelectric hybrid further accelerates charge transfer and regulates the O2 activation pathway. As a result, the Ag-PCN/SnO2- x catalyst efficiently activates O2 into ·O2 - , ·OH, and H2 O2 under co-excitation of visible light and ultrasound, which are consequently utilized to trigger aerobic degradation of refractory antibiotic pollutants. This work provides a promising strategy to maneuver charge transfer dynamics for efficient piezo-photocatalysis by integrating single-atom catalysts (SACs) with Z-scheme heterojunction.Agency for Science, Technology and Research (A*STAR)National Research Foundation (NRF)Published versionThe authors acknowledge the funding support from the Central Research Fund from the Agency for Science, Technology and Research (A*STAR), Singapore, National Research Foundation of Singapore (Grant No. NRF-CRP24-2020-0002) and Natural Science Foundation of China (21725102)