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

Insights into copper(I) phenylacetylide with in-situ transformation of oxygen and enhanced visible-light response for water decontamination: Cu-O bond promotes exciton dissociation and charge transfer

The widespread contamination of hexavalent chromium (Cr(VI)), pharmaceuticals and personal care products (PPCPs), and dyes is a growing concern. necessitating the development of convenient and effective technologies for their removal. Copper(I) phenylacetylide (PhC2Cu) has emerged as a promising photocatalyst for environmental remediation. In this study, we introduced a functional Cu-O bond into PhC2Cu (referred to as OrPhC2Cu) by creatively converting the adsorbed oxygen on the surface of PhC2Cu into a Cu-O bond to enhance the efficiency of Cr(VI) photoreduction, PPCPs photodegradation, and dyes photodegradation through a facile vacuum activating method. The incorporation of the Cu-O bond optimized the electron structure of OrPhC2Cu, facilitating exciton dissociation and charge transfer. The exciton dissociation behavior and charge transfer mechanism were systematically investigated for the first time in the OrPhC2Cu system by photoelectrochemical tests, fluorescence and phosphorescence (PH) techniques, and density functional theory (DFT) calculations. Remarkably, the enhanced visible-light response of OrPhC2Cu improved photon utilization and significantly promoted the generation of reactive species (RSs), leading to the highly efficient Cr(VI) photoreduction (98.52% within 25 min) and sulfamethazine photodegradation (94.65% within 60 min), with 3.91 and 5.23 times higher activity compared to PhC2Cu. Additionally, the photocatalytic efficiency of OrPhC2Cu in degrading anionic dyes surpassed that of cationic dyes. The performance of the OrPhC2Cu system in treating electroplating effluent or natural water bodies suggests its potential for practical applications.

Copper Phenylacetylide and TiO2 Modification for an Efficient Visible-Light-Driven Oxidative Coupling of Amines

The selective oxidation of amines to imines under mild conditions has attracted much attention. Our study reveals that copper phenylacetylide (PhC2Cu) could serve as an efficient photocatalyst for imine synthesis under visible-light irradiation (>400 nm). Utilizing benzylamine as a model reactant, PhC2Cu achieves an imine yield of 50.4%, which is 5 times higher than that of P25 under the same conditions and comparable to the yield obtained by the 3 wt % Au/P25 photocatalyst (55.4%). Further loading 3.9 nm TiO2 onto PhC2Cu through tetrabutyl titanate hydrolysis increases the imine yield to 84.7%, with a Ti:Cu atomic ratio of 3.65%. Control experiments, photoluminescence (PL) spectra, optical pump terahertz probe (OPTP) spectra, and electron spin resonance (ESR) tests confirm that the optimized TiO2 modification promotes the separation of excited carriers and electron transfer in PhC2Cu and facilitates the activation of surface oxygen, thereby enhancing the formation of superoxide radicals, a key active oxygen species in the reaction system. This work presents a promising strategy for efficient imine synthesis via amine coupling and expands the application field of PhC2Cu-based photocatalysts.

Degradation of sulfonamide antibiotic via UV/MgO2 system: kinetic, application, and mechanism

In response to antibiotic residues in the water, a novel advanced oxidation technology based on MgO2 was used to remediate sulfamethazine (SMTZ) pollution in aquatic environments. Upon appropriate regulation, the remarkable removal efficiency of SMTZ was observed in a UV/MgO2 system, and the pseudo-first-order reaction constant reached 0.4074 min-1. In addition, the better performance of the UV/MgO2 system in a weak acid environment was discovered. During the removal of SMTZ, the pathways of SMTZ degradation were deduced, including nitration, ring opening, and group loss. In the mineralization exploration, the further removal of residual products of SMTZ by the UV/MgO2 system was visually demonstrated. The qualitative and quantitative researches as well as the roles of reactive species were valuated, which revealed the important role of ·O2-. Common co-existing substances in actual wastewater such as NO3- HA, Cl-, Fe2+, Co2+, and Mn2+ can slightly inhibit the degradation of SMTZ in the UV/MgO2 system. Finally, the capacity of efficient degradation of SMTZ in actual wastewater by the UV/MgO2 system was proved. The results indicated that the innovative UV/MgO2 system was of great practical application prospect in antibiotic residue wastewater remediation.

Reasonable decoration of CuO/Cd0.5Zn0.5S nanoparticles onto flower-like Bi5O7I as boosted step-scheme photocatalyst for reinforced photodecomposition of bisphenol A and Cr(VI) reduction in wastewater

Building S-scheme heterostructures is a sophisticated approach to receiving outstanding catalysts for environmental detoxification. Herein, ternary CuO/Cd0.5Zn0.5S/Bi5O7I (CO/CZS/BOI) nanocomposites were constructed by in-situ decorating of CuO and Cd0.5Zn0.5S nanoparticles onto Bi5O7I micro-sphere in a facile route. The optimal CO/CZS/BOI reflected reinforced bisphenol A (BPA) photo-oxidation (95% in 70 min) and Cr(VI) photo-reduction (96.6 in 60 min) under visible light. Besides, CO/CZS/BOI afforded 5.10 (4.44), 4.42 (3.71), and 6.60 (5.27) fold reinforcement in the BPA (Cr(VI)) photo-reaction rate compared to BOI, CZS, and CO, respectively. This behavior was linked to the development of S-scheme mechanisms resulting from the co-effects of BOI, CZS, and CO in retaining the optimum redox capacity, facilitating the dissolution of photo-carriers, increasing reactive sites, and strengthening the visible-light response. The parameters influencing the catalytic reaction of CO/CZS/BOI, such as light intensity, catalyst dosage, and pH, were deeply studied. The quenching tests declared the prominent roles •O2- and •OH in the breaking down of BPA and the participation of electrons and •O2- in the photocatalytic conversion of Cr(VI). The cyclic tests verified the robust photostability of CO/CZS/BOI, which is associated with the reintegration process between the free h+ coming from CZS and the photo-induced e- of CO and BOI in the S-scheme system. In conclusion, the present study provides a profound understanding of the photo-reaction mechanism of CO/CZS/BOI and introduces a novel concept for constructing a superior dual-Scheme system for efficient wastewater detoxification.

Self-assembly construction of 1D carbon nitride nanotubes and cobalt-modified for superior photocatalytic degradation of sulfonamide antibiotics

In the present work, a cobalt-doped carbon nitride nanotubes (Co-CNt) was synthesized via self-assembly process. Contributed to the narrow band gap, enlarged specific surface area and abundant active sites, Co-CNt has excellent photoelectric properties and superior performance than pristine CN in sulfisoxazole (SIZ) degradation under blue light irradiation, which achieved 100% removal within 40 min. Meanwhile, the system not only exhibited practical applicability by efficiently degrading SIZ, but also generating high levels of H2O2. Moreover, the Co-CNt/visible light system shows superior operability over a wide pH range, micro-concentration contaminants, various anions, water matrices and other sulfonamides with promising catalytic stability and applicability. The contribution of RSs in the degradation process were elucidated based on radical scavenging and spin-trapped tests, clarifying that O2·- and h+ majorly dominated the process. In addition, 4 probable degradation pathways of SIZ were provided and the generated intermediates' toxicity were evaluated. Overall, this study successfully synthesized a self-assembled 1D tubular photocatalyst with Co-doped and demonstrated the potential Co-CNt/visible light system for environmental remediation, providing a promising approach for the development of photocatalysis.

Carbon nitride nanotubes anchored with Cu(I) triggers peracetic acid activation with visible light for removal of antibiotic contaminants: Probing mechanisms of non-radical pathways and identifying active sites

The peracetic acid (PAA)-activation process has attracted much attention in wastewater treatment. However, the low electron efficiency at the interface between heterogeneous catalysts and PAA has affected its practical application. For this study, we developed a carbon nitride hollow-nanotube catalysts with dispersed Cu(I) sites (Cu(I)-TCN) for the photocatalytic activation of PAA for antibiotics degradation. The obtained Cu(I)-TCN catalyst demonstrated an enhanced capacity for visible light harvesting along with increased charge transfer rates. Specifically, the developed Cu(I)-TCN/visible light/PAA system was able to completely remove antibiotics within 20 min, with a kinetic constant that was 25 times higher than a Cu(I)-TCN/visible light system, and 83 times higher than Cu(I)-TCN/PAA systems. Scavenging experiment and electron paramagnetic resonance (EPR) indicated that singlet oxygen was dominant reactive specie for sulfisoxazole (SIZ) removal. Besides, electrochemical tests and attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy verified that the electron transfer efficiency of PAA activation was promoted due to the formation of inner-sphere interactions between PAA and Cu(I)-TCN, resulting in the quick removal of antibiotics. Further, after exposure to visible light, the Cu(I)-TCN excited photogenerated electrons which supplemented the electrons consumed in the reaction and drove the valence cycle of Cu ions. Overall, this research offered novel insights into the non-radical pathway for heterogeneous visible light-driven advanced oxidation processes and their potential for practical wastewater remediation.

Embedding CsPbBr3 Quantum Dots into an In2O3 Nanotube for Selective Photocatalytic CO2 Reduction to Hydrocarbon Fuels

Halide perovskite quantum dots (QDs) are one of the most prospective candidates for photocatalytic CO2 reduction, but their photocatalytic performances are far from satisfactory due to structural instability and severe charge recombination. In this study, we demonstrated a CsPbBr3 QDs/In2O3 hierarchical nanotube (CPB/IO) for efficient CO2 conversion, in which CsPbBr3 QDs were well-dispersed on the In-MOF-derived In2O3 nanotube by a facile self-assembly process. The optimized CPB/IO catalyst displayed an enhanced photocatalytic CO2 performance with a (CO + CH4) generation rate of 16.37 μmol·g-1·h-1 upon simulated solar illumination without a photosensitizer and sacrificial agent, which is 3.59 times stronger than that of pristine CsPbBr3 QDs (4.56 μmol·g-1·h-1). Besides, the modified CsPbBr3 QD catalyst exhibited an obvious increase of CH4 selectivity and excellent stability after four cycles. The unique zero-dimensional (0D)/one-dimensional (1D) heterostructure and matching band potentials between CsPbBr3 and In2O3 supply an intimate interfacial contact, numerous active sites, and effective charge transfer for CO2 photoreduction. This work can inspire the formation of novel halide-perovskite-involving photocatalysts for solar fuel formation.

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.

Fabrication of an S-Scheme Heterojunction Photocatalyst MoS2/PANI with Greatly Enhanced Photocatalytic Performance

As a promising catalyst, MoS2 has been widely studied owing to its high chemical reactivity, excellent electrical carrier mobility, good optical properties, and narrow band gap. However, the high recombination rate of photoinduced charge carriers limits its practical application in photocatalysis. In this study, MoS2 was coupled with PANI to fabricate an S-scheme heterojunction MoS2/PANI. The synthesized products were characterized systematically, and their photocatalytic properties were evaluated by photocatalytic degradation of norfloxacin (NOR) and rhodamine B (RhB). The obtained results indicated that the fabricated MoS2/PANI inorganic-organic heterojunction displayed tremendously enhanced photocatalytic activity. The degradation efficiencies for 60 mg L-1 of NOR and RhB are 86 and 100% under the simulated sunlight irradiation for 1 h with 10 mg of catalyst, which are 13 and 47 times higher than those of pure MoS2, respectively. Interestingly, it is superior to the previously reported related materials. The remarkably enhanced photocatalytic activity of MoS2 is assigned to the high charge conductivity feature of PANI and the formed S-scheme heterojunction that result in a steric separation of holes and electrons and conserve the initial powerful redox ability of the parent catalysts. This study provides a facile method to greatly improve the photocatalytic activity of MoS2 and facilitates its application for highly efficient removal of organic pollutants, such as antibiotic drugs and organic dyes, utilizing solar energy.

Leaf-like ionic covalent organic framework for the highly efficient and selective removal of non-steroidal anti-inflammatory drugs: Adsorption performance and mechanism insights

In recent years, ionic covalent organic frameworks (iCOFs) have become popular for the removal of contaminants from water. Herein, we employed 2-hydroxybenzene-1,3,5-tricarbaldehyde (TFP) and 1,3-diaminoguanidine monohydrochloride (Dg_Cl) to develop a novel leaf-like iCOF (TFP-Dg_Cl) for the highly efficient and selective removal of non-steroidal anti-inflammatory drugs (NSAIDs). The uniformly distributed adsorption sites, suitable pore sizes, and functional groups (hydroxyl groups, guanidinium groups, and aromatic groups) of the TFP-Dg_Cl endowed it with powerful and selective adsorption capacities for NSAIDs. Remarkably, the optimal leaf-like TFP-Dg_Cl demonstrated an excellent maximum adsorption capacity (1100.08 mg/g) for diclofenac sodium (DCF), to the best of our knowledge, the largest adsorption capacity ever achieved for DCF. Further testing under varying environmental conditions such as pH, different types of anions, and multi-component systems confirmed the practical suitability of the TFP-Dg_Cl. Moreover, the prepared TFP-Dg_Cl exhibited exceptional reusability and stability through six adsorption-desorption cycles. Finally, the adsorption mechanisms of NSAIDs on leaf-like TFP-Dg_Cl were confirmed as electrostatic interactions, hydrogen bonding, and π-π interactions. This work significantly supplements to our understanding of iCOFs and provides new insights into the removal of NSAIDs from wastewater.