Micropollutants are ubiquitous in water sources, posing threats to both human health and ecosystems. Conventional water and wastewater treatment processes are inefficient in micropollutant removal. In this study, the energy-effective and environmentally friendly solar light–driven periodate (PI) and peroxydisulfate (PDS) synergistic activation process (PI/PDS/solar light) is developed for efficient micropollutant decontamination. The PI/PDS/solar light process (0.5 mM PI and 0.25 mM PDS) achieves 100

The frequent occurrence of antibiotics in wastewater poses a serious threat to human health and ecosystem safety. High-valent cobalt-oxo (Co(IV)=O) is a promising reactive species for antibiotic degradation, however, the selective and highly efficient generation of Co(IV)=O in advanced oxidation processes (AOPs) remains challenging. Herein, we develop a photoelectrochemical peroxymonosulfate activation (PEC/PMS) system using a cobalt-doping MoS2@CC (Co-MoS2@CC) photoanode to generate Co(IV)=O for efficient antibiotic degradation. The Co doping significantly improves the PEC properties of Co-MoS2@CC and increases its active sites, achieving a high sulfamethoxazole (SMX) degradation rate constant (0.497 min(-1)) in the PEC/PMS system. Mechanistic investigations reveal that the PEC system activates PMS through a non-radical pathway to selectively form Co(IV)=O (with a high steady-state concentration of 1.95 x 10(-9) M) in-situ on Co-MoS2@CC as the dominant reactive species for SMX degradation (93.4% contribution). The photogenerated holes are a critical driving force for Co(IV)=O formation, while the photogenerated electrons accelerate the valence cycling of Co species to facilitate Co(IV)=O generation. Additionally, the PEC/PMS treatment significantly reduces SMX toxicity by efficiently disrupting its molecular structure. Furthermore, the PEC/PMS system demonstrates excellent practicality, evidenced by stably producing Co(IV)=O under pH 5 similar to 9 and effectively degrading five frequently detected antibiotics in real wastewater over five cycles. The study provides in-depth insight into the rational design of the PEC/PMS system for the selective formation of Co(IV)=O.

Conventional water treatment plants are found to be incapable of degrading pharmaceuticals and personal care products (PPCPs), thereby imposing high risks to human health. As a solution to the deficiency of conventional water treatment plants, although the photocatalysis (PC)/chlorine process has been demonstrated to be feasible for incorporating PPCP degradation and disinfection, its development has been limited by the rapid recombination of charge carriers, secondary pollution, and intense formation of disinfection byproducts (DBPs). To overcome these limitations of the PC/chlorine process, we have developed a novel photoelectrochemical (PEC)/chlorine system with enhanced charge separation forced by external bias in this study. A dual-vacancy-engineered BiVO4 (V-Bi,V-O-BiVO4) photoanode with improved PEC properties was synthesized for the PEC/chlorine system, which can prevent secondary disinfection by immobilizing the photocatalyst. The effectiveness of the PEC/chlorine system is shown by achieving an enhanced carbamazepine (CBZ, a PPCP) degradation rate constant of 0.065 min(-1) (compared with 0.041 min(-1) for the PC/chlorine system) and complete inactivation of 3-log/mL E. coli within 1 min in a batch reactor. The mechanistic study reveals that both photogenerated electrons and holes engage in chlorine activation, producing (OH)-O-center dot and (OCl)-O-center dot as the predominant reactive species for PPCP degradation. Notably, compared to the PC/chlorine process, the PEC/chlorine system reduces DBP formation by 44.6 %, ensuring the safety of the treated water. Furthermore, the scalability of the PEC/chlorine system from a batch to continuous flow reactor is proven by achieving excellent performance in PPCP degradation and E. coli disinfection with a low power-intensive UV light source. This study provides detailed insights into the potential applications of the PEC/chlorine process for PPCP degradation and disinfection in future water treatment processes.

The solar/chlorine process provides an energy-efficient technique for the abatement of some pharmaceuticals and personal care products (PPCPs) but it is inefficient in degrading PPCPs lacking electron-donating group and suffers high formation of disinfection byproducts (DBPs). In this study, a photothermal approach is developed to promote chlorine activation (photothermal/chlorine) under solar radiation to effectively remove a wide range of structurally diverse PPCPs and to control DBPs formation. To this end, a carbon black (CB) coated 3D porous melamine sponge (MS), namely CB@MS, is developed for the photothermal/chlorine application, achieving significantly enhanced PPCPs degradation with an ibuprofen (IBU) removal rate constant (0.22 min-1) 3.76 times that of the solar/chlorine process (0.058 min-1). Mechanistic investigations revealed that CB@MS confines the thermal energy within the 3D porous structure to achieve high localized heating for boosting PPCPs degradation in the confined space, which is equivalent to the thermal effect achieved by the solar/chlorine process at constant solution temperature of around 70 degrees C. Moreover, the photothermal/chlorine process reduces TOCl and DBPs formation by 77.6 % and 67.5 %, ascribed to adsorption by CB@MS, less chlorine exposure, and altered PPCPs degradation pathways. The broad applicability in various water matrices, and good reusability and stability of the photothermal/chlorine system also ensure its excellent practicality. This study offers in-depth mechanisms and practical insights into the development of a novel photothermal/chlorine process for PPCPs abatement and DBPs control.

Phosphate removal and recovery from contaminated water are crucial in addressing eutrophication and global phosphorus (P) scarcity. Conventional adsorption reactors and adsorbent regeneration techniques fall short of meeting the demands for efficient phosphorus removal and recovery. This study, for the first time, presents a semi -fluidized reactor using La2(CO3)3-loaded anion -exchange resin (LC@AER) for enhanced phosphorus removal and in -situ adsorbent regeneration. The response surface methodology (RSM) analysis identifies the ideal conditions for optimizing adsorption efficiency and highlights the substantial influence of pH and sulfate concentration on the phosphate adsorption capacity. The Thomas and Yoon-Nelson models exhibit excellent fits with breakthrough curves (R2>0.99), facilitating the determination of the adsorbent dosage for practical applications. In the semi -fluidized reactor, LC@AER performs efficiently in five adsorption-desorption cycles with an average adsorption capacity of 44.67 mg/g and a regeneration efficiency of 92.22%, achieving enhancements of 86.8% for phosphate adsorption and 61.22% for adsorbent regeneration (compared with fixed -bed columns using LC@AER). These results demonstrate that the semi -fluidized reactor enables LC@AER to achieve excellent reusability, ensuring its promising industrialization prospects. The enhanced performance is attributed to the semi -fluidized reactor offering better interaction between the adsorbent and liquid and overcoming issues of the dead zone and channeling. This study has substantial significance for sustainable phosphorus pollution management and provides key parameters for potential industrial -scale applications of this process.

Conventional wastewater treatment plants (WWTPs) face challenges due to high carbon emissions and energy consumption. Herein, a low-carbon-emission photoelectrochemical (PEC) system using an oxygen-vacancy-rich Fe2O3@BiVO4 (Ov-Fe2O3@BiVO4) photoanode that is aimed at replacing biological treatment and disinfection, is developed to simultaneously remove organic compounds, ammonia (NH4+-N), and bacteria from real saline sewage (after primary treatment) while generating green H2. The PEC system demonstrates remarkable performance in the treatment of real saline sewage, as evidenced by the fact that the treated sewage is able to meet local discharge standards of chemical oxygen demand (COD), ammonia-N, and Escherichia coli (E. coli) after two hours of operation under simulated solar light at 2.0 V (vs. Ag/AgCl). Most importantly, it generates 11.51 mol/m3 of green H2 (equal to 0.458 kWh/m3 of electricity) and results in notable reductions of 76.7 % in scope 1 emissions (direct GHG emissions) and 62.5 % in total carbon emissions compared to conventional WWTPs. The scavenging tests and estimated steady-state concentrations of reactive species indicate that Cl•, ClO•, and Cl2•− are the primary contributors to the degradation of organic pollutants, while ClO• is dominant in converting ammonia to N2. Additionally, the excellent reusability, stability and easy regeneration of the Ov-Fe2O3@BiVO4 photoanode and its good performance in treating different batches of real sewage guarantee the high practicability of the PEC system. This study has successfully validated the PEC system as a low-carbon-emission technology approach for saline sewage treatment coupled with green H2 generation, demonstrating its enormous practical potential.

Global warming intensifies heat stress, posing substantial challenges to cultivated plants and agricultural yield production. The high solar absorptance of soil results in elevated temperatures, pushing plants beyond their ideal growth range. Additionally, this rise in soil temperature accelerates soil moisture evaporation, further aggravating existing water scarcity issues. Common cooling solutions tends to consume significant amounts of water or offer limited cooling capacities. In response, a radiative cooling and moisturizing film composed of biodegradable ethyl-cellulose was developed. With a solar reflectance of 97% and a thermal emissivity of 0.93, this film provides efficient zero-energy cooling for soil surfaces. Field tests have demonstrated that compared to commercial cooling mulch, the radiative cooling film significantly reduces soil temperature and moisture evaporation by 50% and 60%, respectively. Furthermore, it boosts plant growth by 30% by moderating leaf temperatures and augmenting the exposure to reflected sunlight, crucial for photosynthesis on hot days. Global heat-water simulations reveal that the film increases soil moisture preservation by over 80% and alleviates agricultural water scarcity by over 60% in arid regions during hot seasons. This work offers a practical and sustainable solution to mitigate heat stress and promote resilient cultivation practices in the context of global warming.

Micropollutants and bacteria are prevalent pollutants in wastewater, posing significant risks to ecosystems and human health. As peracetic acid (PAA) is being increasingly used as a disinfectant, activation of PAA by low-cost and high-performance activators is a promising strategy for wastewater treatment. In this study, the sulfur-doped magnetic CoFe2O4 (SCFO) is successfully developed for efficient PAA activation to simultaneously decontaminate and disinfect wastewater. PAA/SCFO-0.3 exhibits exceptional performance, degrading 100% of 8 μM sulfamethoxazole (SMX) with a first-pseudo reaction rate of 1.275 min−1, and achieving 5.3-log inactivation of Escherichia coli (E. coli) within 3 min at a PAA dosage of 0.2 mM and catalyst dosage of 0.025 g/L (initial pH 6.5). Scavenging experiments and electron paramagnetic resonance (EPR) analysis identify CH3C(O)O• and CH3C(O)OO• as the dominant reactive species for SMX degradation. The sulfur species in SCFO-0.3 facilitate Co2+ regeneration and regulate charge transfer, promoting PAA activation for SMX degradation. Moreover, the PAA/SCFO-0.3 system demonstrates operational feasibility over a broad range of water matrices and has excellent stability and reusability (maintaining 93% removal of SMX after 5 cycles), demonstrating its potential for industrial applications. This study provides insights into enhancing PAA activation through sulfur doping in transition metal catalysts and highlights the practical applicability of the PAA/SCFO-0.3 system as an advanced alternative to conventional disinfection for simultaneous decontamination and disinfection in wastewater.

Lanthanum carbonate @ anion exchange resin (LC@AER) has shown promise in adsorption processes due to its high maximum adsorption capacity and excellent stability in comparison with other lanthanum-based adsorbents. Nevertheless, there is a lack of significant investigation in evaluating the collective effect of the most influential parameters and determining the molecular complexes between the adsorbent and phosphate. This work aims to comprehensively evaluate and optimize the phosphate adsorption performance in fixed-bed columns and to determine the most favourable molecular configurations. Firstly, a response surface model (RSM) was developed to describe the phosphate adsorption performance in fixed-bed columns under the collective effect of selected independent variables, including influent pH, co-existing sulfate concentration, and empty bed contact time (EBCT). The RSM analysis reveals the significant effects of influent pH and co-existing sulfate concentration on phosphate adsorption. Moreover, the model achieves a correlation coefficient of >0.9, demonstrating its suitability for describing the experimental data. Secondly, various phosphate-lanthanum carbonate configurations were formulated, and the respective adsorption energies were compared using density functional theory (DFT) calculations. Subsequently, bidentate mononuclear complexes are determined as the most favourable configurations. The successful matching of the simulated peak locations with the experimental deconvoluted spectra further confirms the presence of such complexes in the system. Overall, this work provides an improved foundation and underlayer theory for potential future scale-up work on phosphate adsorption over LC@AER.

The critical review covers the applications, associated mechanisms, challenges, and prospects of magnetically recyclable nanophotocatalysts in photocatalysis-related processes.

Pharmaceuticals and personal care products (PPCPs) are ubiquitous in sewage, adversely affecting ecosystems and human health. In this study, an S-scheme magnetic ZnFe2O4/ammoniated MoS2 (ZnFe2O4/A-MoS2) heterojunction as a visible-light-driven PMS activator for PPCP degradation was developed. ZnFe2O4/A-MoS2 achieves improved photocatalytic activity because the construction of S-scheme heterojunction promotes the separation of the highly reductive photogenerated electrons. The optimized photocatalyst (10%-ZnFe2O4/A-MoS2, 0.2 g/L) achieved 100% removal of 2 ppm carbamazepine (CBZ) within 2.5 min at a PMS dosage of 0.5 mM (initial pH 7.0). Mechanistic investigation revealed that the separated electrons to the ZnFe2O4 reactive center of the heterojunction facilitated PMS activation and generated SO4·- as the dominant reactive species for CBZ degradation. The system exhibited excellent practicability in various samples of actual sewage, where most sewage components negatively impacted CBZ degradation. Further, the chloride ions in high-salinity sewage could be activated to generate additional reactive chlorine species for PPCP degradation. The heterojunction possesses outstanding reusability and stability in treating various water conditions. This work provides mechanistic and practical perspectives in developing novel S-type heterojunctions for recalcitrant pollutant treatment.

Abstract Agriculture faces pressing challenges of heat stress and water scarcity due to climate change. While mulching is a common solution, traditional mulching materials lack sub-ambient cooling capabilities and biodegradability, resulting in elevated soil temperature, increased moisture evaporation, exacerbated global agricultural heat-water crisis, and soil microplastics pollution. Herein, we have developed a biodegradable and biocompatible ethyl-cellulose radiative cooling mulch with a solar reflectance and thermal emissivity of 97% and 0.93, respectively, to provide zero-energy cooling for soil surfaces. Field tests have demonstrated that the radiative cooling mulch significantly reduces soil moisture evaporation by 60% through cooling soil surfaces, while also improves plant growth by 30% through reducing crop leaf temperature and increasing sunlight exposure for photosynthesis in hot days. Moreover, global heat-water nexus simulations show that the mulch increases soil moisture preservation by over 80% and alleviates agricultural water scarcity by over 60% in arid regions during hot seasons. The work offers an eco-friendly and feasible pathway to foster sustainable agriculture by alleviating heat stress and water scarcity in the context of global warming.

The inefficiency of conventional water treatment technologies for the treatment of antibiotics has become a global concern. Herein, a promising photoelectrocatalytic (PEC) system enhanced by PMS was developed to treat antibiotics in drinking water in which a modified molybdenum disulfide embedded carbon cloth photoanode (namely 1T/2H-MoS2@C/CC, 1T and 2H for hexagonal and trigonal structures) served as a photoanode. The 1T/2H-MoS2@C/CC photoanode exhibited enhanced PEC performance due to the construction of the 1T rich structure. Under the synergetic effect of PEC and PMS, 2 ppm norfloxacin was completely removed in 30 min by the 1T/2H-MoS2@C/CC photoanode at a 1.5 V applied potential with 40 ppm PMS addition. Mechanistic investigations demonstrated that O-1(2), HO center dot, SO4 center dot- and O-2(center dot-) contributed to norfloxacin degradation, and the PMS activation pathways for the generation of these reactive species were also revealed. The intermediates of NOR degradation by the PEC/PMS system were analyzed, suggesting that the C-N bond, piperazine ring, and fluoride group on NOR molecular framework were attacked. The resistance of the PEC/PMS system to different water matrices and good reusability (87.6% at the fifth cycle) and stability (0.05 mg/L Mo4+ leaching) of the 1T/2H-MoS2@C/CC photoanode ensured the excellent practical potential of the developed PEC/PMS system. Overall, the PEC/PMS system with 1T/2H-MoS2@C/CC as the photoanode is proven to be feasible for practical antibiotics removal from drinking water.

Conventional wastewater treatment plants (WWTPs) suffer from high carbon emissions and are inefficient in removing emerging organic pollutants (EOPs). Consequently, we have developed a low operational carbon emissions multifunctional photoelectrochemical (PEC) system for saline sewage treatment to simultaneously remove organic pollutants, ammonia, and bacteria, coupled with H2 evolution. A reduced BiVO4 (r-BiVO4) photoanode with enhanced PEC properties, ascribed to constructing sufficient oxygen vacancies and V4+ species, was synthesized for the aforementioned technique. The PEC/r-BiVO4 process could treat saline sewage to meet local WWTPs' discharge standard in 40 min at 2.0 V vs Ag/AgCl and completely degrade carbamazepine (one of EOPs), coupled with 633 μmol of H2 production; 93.29% reduction in operational carbon emissions and 77.82% decrease in direct emissions were achieved by the PEC/r-BiVO4 process compared with large-scale WWTPs, attributed to the restrained generation of CH4 and N2O. The PEC system activated chloride ions in sewage to generate numerous reactive chlorine species and facilitate •OH production, promoting contaminants removal. The PEC system exhibited operational feasibility at varying pH and total suspended solids concentrations and has outstanding reusability and stability, confirming its promising practical potential. This study proposed a novel PEC reaction for reducing operational carbon emissions from saline sewage treatment.

The inefficiency of conventional water treatment technologies for the treatment of antibiotics has become a global concern. Herein, a promising photoelectrocatalytic (PEC) system enhanced by peroxymonosulfate (PMS) was developed to treat antibiotics in drinking water in which a modified molybdenum disulfide embedded carbon cloth photoanode (namely 1T/2H-MoS2@C/CC) served as a photoanode. The 1T/2H-MoS2@C/CC photoanode exhibited enhanced PEC performance due to the construction of the 1T rich structure. Under the synergetic effect of PEC and PMS, norfloxacin was completely removed in 30 minutes by the 1T/2H-MoS2@C/CC photoanode at a 1.5 V applied potential with 40 ppm PMS addition. Mechanistic investigations demonstrated that 1O2 was the dominant reactive species for norfloxacin (NOR) degradation, and the PMS activation pathways for 1O2 generation were also revealed. The intermediates of NOR degradation by the PEC/PMS system were analyzed, suggesting that the C-N bond, piperazine ring, and fluoride group on NOR molecular framework were attacked. The resistance of the PEC/PMS system to different water matrices and good reusability and stability of the 1T/2H-MoS2@C/CC photoanode ensured the excellent practical potential of the developed PEC/PMS system. Overall, the PEC/PMS system with 1T/2H-MoS2@C/CC as the photoanode is proven to be feasible for practical antibiotics removal from drinking water.

Removal of pharmaceuticals and personal care products (PPCPs) is often inefficient during conventional water treatment, posing threats to human health. Herein, we have developed a novel solar/TiO2/chlorine system upgraded from chlorine disinfection for the simultaneous degradation of PPCPs and the inactivation of Escherichia coli from drinking water. The addition of 100 μM of chlorine to the photocatalytic process considerably enhanced the degradation efficiency of PPCPs and demonstrated excellent disinfecting abilities, as confirmed by a 4.7 × increase in the carbamazepine degradation rate constant coupled with a 3.2-log (99.94%) reduction of E. coli cells within 1 min. Photoinduced charge pairs (hVB+ and eCB-) were identified for reactive species generation, and HO• and ClO• were the primary contributors to PPCPs degradation. The process exhibited satisfactory carbamazepine degradation efficiency in different water matrices and the cycling tests showed the TiO2 photocatalyst to be highly stable and reusable. Overall, our solar/TiO2/chlorine system is a potentially effective alternative to conventional drinking water treatment using chlorination.

A new photoelectrochemical (PEC) system by means of adding sodium sulfite (Na2SO3) was developed to treat sewage. The PEC system simultaneously promoted pharmaceuticals and personal care products (PPCPs) degradation, H-2 evolution and E. roll disinfection using an optimized, visible-light driven BiVO4 photoanode. The PEC reactions were first carried out in 1.5 mM Na2SO3 electrolyte. 92.3% of 2 ppm benzophenone-3 (BZP) was degraded, and 115.36 kimol of H-2 was produced in 90 mM at 1.0 V vs. Ag/AgCl, which was a significant improvement over cases where the electrolyte was either Na2SO4 or NaCl. The sulfite ions were first activated by holes and then converted into sulfate radicals, which played a dominant role in the degradation of BZP. As the holes were caught by the sulfite, charge separation was also enhanced, increasing H-2 evolution. The PEC reactions were also used to treat real sewage, in which case an 82% improvement in the rate constant of BZP degradation, 60% increase of H-2 evolution, and 0.78 log enhancement of E. roll disinfection were achieved by adding 1.5 mM Na2SO3. The system was also feasible to degrade various PPCPs, and showed excellent reusability and stability, proving its great potential in sewage treatment.

A solar-light-driven magnetic photocatalyst, reduced-graphene-oxide/Fe,N-TiO2/Fe3O4@SiO2 (RGOFeNTFS), was developed for the photocatalytic disinfection of different strains of bacteria: gram-negative Escherichia coli (E. coli) and Salmonella typhimurium (S. typhimurium), and gram-positive Enterococcus faecalis (E. faecalis). The different responses of the bacteria during the reaction were investigated. Gram-positive E. faecalis was found to be more susceptible to photocatalytic disinfection and exhibited a higher leakage of intracellular components than the two gram-negative bacteria. The interactions between the bacteria and RGOFeNTFS were analyzed for Zeta potential, hydrophilicity and SEM. Under the experimental conditions, the opposite surface charges of the bacteria (negative Zeta potential) and RGOFeNTFS (positive Zeta potential) contribute to their interactions. With a more negative Zeta potential (than E. coli and E. faecalis), S. typhimurium interacts more strongly with RGOFeNTFS and is mainly attacked by •OH near the photocatalyst surface. E. coli and E. faecalis (with less negative Zeta potentials) interact less strongly with RGOFeNTFS, and compete for the dominant reactive species (•O2-) in the bulk solution. Therefore, the co-existence of bacteria significantly inhibits the photocatalytic disinfection of E. coli and E. faecalis, but insignificantly for S. typhimurium. Moreover, photocatalytic disinfection using RGOFeNTFS show potential for treating real sewage, which meets the local discharge standard (of E. coli) after a 60-min reaction. In real sewage, different bacteria are disinfected simultaneously.

Tip-decorated ZnO/Bi2S3 photoelectrode was synthesized on a FTO substrate from chemical bath deposition and electrochemical deposition to investigate the photoelectrocatalytic (PEC) degradation of tetrabromobisphenol A (TBBPA). XRD, SEM, UV-vis and PL techniques were employed to evaluated the crystal structure, surface morphology, light absorbance properties and efficiency of carriers' separation of the obtained electrode, respectively. The ZnO/Bi2S3 photoelectrode yielded a photocurrent density of 15.3 mA/cm(2) upon ultraviolet and visible light irradiation, which was 6.6 and 10.9 times that of the original ZnO and Bi2S3, respectively. The enhanced photoelectrochemical properties is due to the improved light absorption of Bi2S3 nanoparticles and accelerated electron-transfer pathway of ZnO nanorods. The stability of the photoelectrode was evaluated by recycling degradation experiments for 3 times. The intermediates of TBBPA degradation were also identified and a possible pathway was proposed.

In recent years, molybdenum disulfides (MoS2) have been widely recognized as a promising catalyst or cocatalyst in Advanced Oxidation Processes (AOPs); however, the discharge of hydrogen sulfide (H2S) after catalytic process is still a key issue that needs to be addressed. Hence, in this study, a superoxide radical (O-2(center dot-)) dominated visible-light-driven peroxymonosulfate activation process has been established by adopting molybdenum selenide (MoSe2) to replace MoS2 in order to dramatically enhance the catalytic degradation efficiency of three types of pharmaceuticals and personal care products (PPCPs) (e.g., ibuprofen, benzophenone-3 and carbamazepine). This enhancement is due to its exposed surface metallic Mo4+ ions, accompanied with the oxidization to Mo5+ and Mo6+ for further participating in the decomposing of PMS, as well as the photo-generated electrons playing a prominent role in reducing the Mo5+ and Mo6+ back to Mo4+. Scavenger tests and electron paramagnetic resonance (EPR) identify the O-2(center dot-) as the primary reactive oxygen species (ROS) in the MoSe2/PMS system, and singlet oxygen (O-1(2)) is mainly derived from the transformation of O-2(center dot-). Density Functional Theory (DFT) is used to explain the elongation of O-O bond in the PMS molecule that would facilitate the generation of sulfate radicals and hydroxyl radicals in both of MoSe2 catalyzed PMS system and cocatalyzed Fe(II) or Fe(III)/PMS systems. Ultimately, the MoSe2/PMS system is also applicable for the treatment of actual sewage. This work highlights the important role of photo-generated electrons and molybdenum ions in PMS reduction and oxidation, and establishes theoretical support for further relevant studies.