Strategy for improvement of molecular oxygen activation capacity of PPECu by chlorine doping for water decontamination.

The activation of molecular oxygen and generation of reactive oxygen species (ROS) play important roles in the efficient removal of contaminants from aqueous ecosystems. Herein, using a simple and rapid solvothermal process, we developed a chlorine-doped phenylethynylcopper (Cl/PPECu) photocatalyst and applied it to visible light degradation of sulfamethazine (SMT) in aqueous media. The Cl/PPECu was optimized to have a 2.52 times higher steady-state concentration of O2•- (3.62 × 10-5 M) and a 28.87 times higher degradation rate constant (0.2252 min-1) for SMT compared to pure PPECu. Further, the effectiveness of Cl/PPECu in treating sulfonamide antibiotics (SAs) in real water systems was verified through an investigation involving natural water bodies, SAs, and ambient sunlight. The energy band structure, DFT calculation and correlation heat map indicated that the addition of chlorine modulated the local electronic structure of PPECu, leading to an improvement in the electron-hole separation, enhanced the O2 activation, and promoted the generation of ROSs. This study not only puts forward innovative ideas for the eco-compatible remediation of environmental pollution using PPECu, but also sheds new light on the activation of oxygen through elemental doping.

Simplified synthesis of direct Z-scheme Bi2WO6/PhC2Cu heterojunction that shows enhanced photocatalytic degradation of 2,4,6-TCP: Kinetic study and mechanistic insights.

For this work, we employed n-type Bi2WO6 and p-type PhC2Cu to formulate a direct Z-scheme Bi2WO6/PhC2Cu (PCBW) photocatalyst via simplified ultrasonic stirring technique. An optimal 0.6PCBW composite exhibited the capacity to rapidly photodegrade 2,4,6-TCP (98.6% in 120 min) under low-power blue LED light, which was 8.53 times and 12.53 times faster than for pristine PhC2Cu and Bi2WO6, respectively. Moreover, electron spin resonance (ESR), time-resolved PL spectra, and quantitative ROS tests indicated that the PCBW enhanced the separation capacity of photocarriers. It also more readily associated with dissolved oxygen in water to generate reactive oxygen species (ROS). Among them, the ability of PCBW to produce ·O2- in one hour was 12.07 times faster than for pure PhC2Cu. In addition, the H2O2 formation rate and apparent quantum efficiency of PCBW are 10.73 times that of PhC2Cu, which indicates that PCBW not only has excellent photocatalytic performance, but also has outstanding ROS production ability. Furthermore, Ag photodeposition, in situ X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations were utilized to determine the photogenerated electron migration paths in the PCBW, which systematically confirmed that Z-scheme heterojunction were successfully formed. Finally, based on the intermediate products, three potential 2,4,6-TCP degradation pathways were proposed.

Facile synthesis of direct Z-scheme UiO-66-NH2/PhC2Cu heterojunction with ultrahigh redox potential for enhanced photocatalytic Cr(VI) reduction and NOR degradation.

Z-scheme heterojunction-based photocatalysts typically have robust removal efficiencies for water contaminants. Herein, we employed p-type PhC2Cu and n-type UiO-66-NH2 to develop a direct Z-scheme UiO-66-NH2/PhC2Cu photocatalyst with an ultrahigh redox potential for Cr(VI) photoreduction and norfloxacin (NOR) photodegradation. Moreover, UV-vis diffuse reflectance, photoelectrochemical measurements, photoluminescence (PL) spectra and electron spin resonance (ESR) technique revealed that the UiO-66-NH2/PhC2Cu composite boosted light capturing capacities to promote photocatalytic efficiencies. Strikingly, the optimized UiO-66-NH2/PhC2Cu50 wt% rapidly reduced Cr(VI) (96.2%, 15 min) and degraded NOR (97.9%, 60 min) under low-power blue LED light. In addition, the UiO-66-NH2/PhC2Cu photocatalyst also exhibited favorable mineralization capacity (78.4%, 120 min). Benefitting from the enhanced interfacial electron transfer and ultrahigh redox potential of the Z-scheme heterojunction, the UiO-66-NH2/PhC2Cu photocatalyst greatly enhanced the separation efficacies of photogenerated carriers. This resulting abundance of active species (e.g., e-, h+, O2•-, and •OH) were generated to photo-reduce Cr(VI) and photo-oxidize NOR. Base on the identified intermediates, four degradation pathways of NOR were proposed. Finally, the Z-scheme mechanism were systematically confirmed through X-ray photoelectron spectroscopy (XPS), ESR, cyclic voltammetry (CV) tests, and photodeposition techniques.

Plasmonic Ag nanoparticles decorated copper-phenylacetylide polymer for visible-light-driven photocatalytic reduction of Cr(VI) and degradation of PPCPs: Performance, kinetics, and mechanism.

The development of efficacious photocatalysts for the elimination of contaminants in water remains a challenge. Herein, a promising Ag nanoparticles-decorated copper-phenylacetylide (Ag/PhC2Cu) plasmonic photocatalyst was fabricated for the reduction of hexavalent chromium (Cr(VI)) and degradation of pharmaceutical and personal care products (PPCPs). Typically, the optimized 5Ag/PhC2Cu could rapidly reduce Cr(VI) (98.1% within 12 min), and degrade norfloxacin (NOR) (100% within 40 min) with a 56.2% mineralization rate under visible light. The superior photocatalytic activity of Ag/PhC2Cu was attributed to the synergistic effects of the highly reducing photoinduced electrons conferred by the PhC2Cu (-1.98 eV), and Ag nanoparticles in promoting photocarrier separation and enhancing solar-energy-conversion efficiencies. Subsequently, the photocatalytic reaction mechanism of Ag/PhC2Cu was investigated. It was found that e- and O2•- were the main reactive species for Cr(VI) reduction, while O2•- and h+ were primarily responsible for the degradation of NOR. Of note, the Ag/PhC2Cu system could effectively generate H2O2 and partially decomposed it to •OH, which might be involved in NOR mineralization. This study not only demonstrates a highly active photocatalytic system for the remediation of environmental pollution and sustainable solar-to-chemical energy conversion, but contributes to the future exploration of multifunctional plasmonic photocatalysts.