Polymerization-based oxidation processes have emerged as a low-carbon-water purification technology for removing organic pollutants. Permanganate (Mn(VII)) can oxidize phenolic pollutants through polymerization; however, this process is currently challenged by the generation of soluble oligomers, resulting in low total organic carbon (TOC) removal and undesired byproducts in effluents. Herein, we demonstrated that incorporating carbon nanotubes (CNTs) into the Mn(VII) system effectively regulated phenol polymerization from soluble oligomers to insoluble multimers, remarkably enhancing TOC removal from 0.5% to 82.0% within 30 min. This remarkable enhancement originated from a synergetic mechanism involving interfacial enrichment and accelerated electron transfer, which promoted the generation of phenoxy radicals and their collisions with phenol and oligomers, thereby driving the polymer chain growth. These synergistic effects overcame the kinetic and steric limitations of the homogeneous Mn(VII) system during phenol oxidation. Quantitative structure-activity relationship analysis revealed the defect-rich and hydrophobic CNTs maximized the above-mentioned synergistic effect, while excessive carboxy contents suppressed phenol polymerization by increasing surface polarity and electrostatic repulsion. Overall, this work provided a simple yet facile strategy for regulating the polymerization products of phenolic pollutants in the Mn(VII) oxidation system, offering fundamental insights for the development of low-carbon and sustainable water treatment technology.

Sewage sludge utilization holds strategic significance for environmental and sustainable goals. This work presents an integrated low-temperature sludge hydrothermal coupled with gel crosslinking strategy, which enables stepwise upgrading of sludge resources into water-treatment materials. Diverging from the current solid-phase-only process, this strategy utilizes the organic components in the hydrothermal liquid for co-crosslinking with sodium alginate, achieving immobilization of hydrothermal constituents. By introducing multifunctional groups and competitively reorganizing the alginate network to expose multidentate adsorption sites, these organic components collectively promote the construction of a hydrothermal-liquid-gel capable of forming high-density metal-O coordination. The hydrothermal-liquid-gel showed up to 47.2% and 368.8% adsorption capacity for heavy metals and antibiotics higher than pure alginate gel, respectively, further reducing residual contaminant concentrations in wastewater by over an order of magnitude. The sludge component in the liquid utilization pathway contributes over three times to pollutant removal that of conventionally focused sludge hydrochar, while maintaining remarkable structure and performance stability across diverse sludge sources through designed regulatory principles. Life cycle assessment and economic analysis demonstrate that sludge integral utilization process maintains economic viability and achieves remarkable carbon reduction benefits. Overall, this work establishes an integrated sludge utilization pathway to construct a sustainable water-energy-resource circulation system.

The electrochemical hydrogen evolution reaction (HER) is a crucial approach to clean, renewable energy, where electrocatalysts are essential. Herein, a series of novel trace platinum-intercalated niobium phosphate hydrate@carbon paper composite electrocatalysts (xPt-NPO@CP) were synthesized via a facile hydrothermal process, exhibiting excellent HER performance in acidic environment with Pt-NPO micro-nanosheets integrated onto carbon paper conductive fibers. The 1.5% Pt-NPO@CP, with 1.5 wt% Pt intercalation, demonstrated superior electrocatalytic HER activity and remarkable long-term durability. Platinum was evenly distributed within the nanosheet structure, providing a large accessible surface area and abundant active interfaces, resulting in a higher electrochemical active surface area, as well as lower catalytic overpotential, Tafel slope, and charge transfer resistance. At current density of 10 and 100 mA.cm(-2), the HER overpotential was only 60.05 and 233.6 mV respectively, with a Tafel slope of 33.39 mV center dot dec(-1). Notably, with exceptional structural and compositional stability, the 1.5%Pt-NPO@CP electrode sustained stable HER performance for 900 h. density functional theory (DFT) calculations revealed that Pt intercalation induced charge redistribution between Pt and the surrounding lattice, modulating the catalyst's electronic structure and promoting Pt atoms as primary active centers for HER, replacing the O-centered sites in pristine NPO. This lowered the reaction energy barrier, accelerated charge transfer kinetics, and resulted in superior catalytic activity toward HER. This work provides an innovative strategy for the development of electrocatalysts, combining high catalytic efficiency with lasting stability and offering considerable application prospects

This work investigated the differences of Co single atom & cluster coupled sites (CoN5-Co-4) compared to single-atom Co sites and Co nanoparticles for peroxymonosulfate (PMS) activation. The porous carbon catalysts with Co sites of different sizes were developed through regulating Co loading amounts onto nitrogen-rich metal-organic frameworks. The catalyst with CoN5-Co-4 sites exhibited higher activity in PMS activation with a rate constant of 17.70 L min(-1) g(-1) for tetracycline degradation, surpassing benchmarks by 1 similar to 2 orders of magnitude. Meanwhile, the fixed-bed reactor with only 100 mg of catalyst enabled continuous complete tetracycline removal in real waters for over 312.5 h. Unlike conventional radical pathways, the catalysis obeyed a surface collision oxidation path. The CoN5-Co-4 sites cooperatively captured PMS to form high-potential complexes that directly oxidized contaminants through electron transfer upon collision. Crucially, tetracycline was converted into low-toxicity products that could be used as microbial carbon sources. Theoretical calculations revealed that compared to single-atom CoN5 site and Co nanoparticle, the CoN5-Co-4 site allowed both efficient PMS enrichment and rapid -HSO4 desorption, thereby maximizing intrinsic activity. Overall, this work could guide the atomic-level optimization of metal sites to enhance antibiotic degradation and provide insight into the synergy between single atoms and clusters.

Zero-valent iron (ZVI) activation of peroxymonosulfate (PMS), especially under weak magnetic fields, provides an effective route to mitigate aggregation and passivation, thereby enhancing wastewater treatment performance. However, the interfacial mechanisms of nanoscale zero-valent iron (nZVI) in PMS activation under weak magnetic fields remain insufficiently resolved. Here, the effects of millitesla-level magnetic fields on interfacial structure, charge transfer, radical generation, and short-range Fe(II)/Fe(III) cycling in the PMS/nZVI system were systematically evaluated. Under the optimal magnetic field of 9.8 mT, methylisothiazolinone (MIT) was almost completely removed within 20 min, and PMS utilization reached 98.2%, approximately twice that under no magnetic field. Microscopic and electrochemical analyses revealed that the magnetic field induced a more ordered and open surface, with a larger accessible area and lower charge-transfer resistance. These changes enhanced the interfacial catalytic activity of nZVI, promoting the generation and rapid consumption of SO4 center dot and center dot OH at the interface, thereby limiting their diffusion into the bulk solution and mitigating anionic quenching. Dissolved iron concentration and zeta (zeta) potential results further indicated that short-range Fe(II)/Fe(III) cycling sustained the interfacial reaction and directed oxidation toward sulfur-centered products, reducing toxicity of approximately 80% of the major products. Moreover, the system exhibited a non-monotonic response to magnetic field strength, revealing a window for efficient interfacial radical utilization. Linking field-driven interfacial evolution with activity, selectivity, and product safety, a mechanism-grounded basis is offered for optimizing weak-field-assisted nZVI/PMS oxidation.

As global efforts intensify toward carbon neutrality and sustainable resource management, wastewater is increasingly recognized as a resource-rich stream rather than a waste. Electrochemical transformation of organic pollutants in wastewater into value-added chemicals offers a sustainable alternative to traditional energy-intensive mineralization processes, aligning with circular economy principles. In this perspective, we first outline the conceptual advantages and recent advances in the electrochemical valorization of organic pollutants. We then discuss its potential application scenarios, with particular emphasis on wastewater sources and the decisive role of pollutant concentration in governing process feasibility. Furthermore, we propose product recovery strategies tailored to the physical states of the target products. Importantly, through preliminary techno-economic and life-cycle analyses, we identify product recovery as a frequently underestimated yet critical bottleneck that potentially dominates the overall economic viability and environmental footprint of electrochemical valorization systems. Finally, we highlight key future research directions to accelerate technological development. Overall, this perspective underscores the potential of electrochemical valorization as a green and efficient approach for simultaneous environmental remediation and resource recovery, with the long-term vision of transforming wastewater treatment plants from energy-intensive cost centers into resource-recovering chemical refineries.

Electrocatalytic hydrogenation (ECH) of aqueous phenol to cyclohexanone and cyclohexanol provides a sustainable strategy for simultaneous pollutant remediation and the synthesis of high-value chemicals. However, in both previous reports and our preliminary experiments, the liquidphase product distributions often suffer from incomplete carbon balance that could not be explained by volatilization, adsorption, membrane crossover, or analytical error. Motivated by this imbalance, a sealed H-cell equipped with a gas-absorption trap was implemented to capture volatile products. A bimetallic PtRu electrode supported on carbon cloth, prepared by cyclic electrodeposition, was then evaluated under ambient conditions. With gas capture, cyclohexane was identified as a co-product with cyclohexanone and cyclohexanol, accounting for the previously “missing” carbon. The PtRu electrode exhibited a superior phenol conversion of 98.9

Water eutrophication remains a critical global challenge, necessitating the development of efficient and easily recoverable adsorbents for deep phosphate removal. In this study, a magnetic cationic hydrogel (MCH) platform was constructed and systematically functionalized with different metal species to obtain high-performance phosphate adsorbents. Among the tested metals, Fe was identified as the most effective primary component, and subsequent incorporation of Al yielded the optimized composite, MCH-Fe3Al7. The obtained material exhibited a three-dimensional porous structure with uniformly dispersed amorphous Fe/Al hydroxylated active sites and superparamagnetic properties. MCH-Fe3Al7 demonstrated rapid and efficient phosphate removal, achieving over 90% uptake within 30 min and a maximum experimental adsorption capacity of 48.24 mg/g. The adsorption behavior was well described by the Langmuir isotherm model (R2 = 0.9863) and pseudo-second-order kinetics ((R2 = 0.9999, qe,cal approximate to qe,exp). Further analysis using the Temkin and Dubinin-Radushkevich (D-R) models revealed an adsorption energy of 16.27 kJ/mol, indicating a chemisorption-dominated process involving inner-sphere Fe/Al-O-P complexation. Thermodynamic analysis (25-35 degrees C) yielded negative Delta G degrees values (-26.54 to-27.23 kJ/mol), a negative Delta H degrees (-13.95 kJ/mol), and a positive Delta S degrees (+42.74 J/(mol & sdot;K)), confirming a spontaneous, exothermic, and entropy-driven adsorption process. The composite reduced phosphate concentrations to below 0.1 mg/L over an initial range of 0.5-5 mg/L and maintained stable performance across pH 5-10 with negligible metal leaching. It also exhibited good tolerance to coexisting ions, retained 75.95% of its initial capacity after five regeneration cycles, and achieved over 99% magnetic separation within 1 min. Notably, comparable deep-removal performance was achieved in real municipal effluent and eutrophic water samples. Mechanistic investigations based on XPS, FTIR, and zeta potential analyses revealed that phosphate removal was governed by synergistic electrostatic enrichment and ligand exchange. The cationic hydrogel matrix facilitated phosphate accumulation, while amorphous Fe/Al hydroxylated sites immobilized phosphate through inner-sphere complexation. The Fe/Al bimetallic system provided an optimal balance between adsorption affinity, structural stability, and low-concentration removal efficiency.

Photocatalytic H2O2 production has emerged as a promising strategy for solar-to-H2O2 energy conversion. However, the inevitable requirement for aeration or sacrificial agents poses great challenges for its further application, particularly in environmental remediation process. Previous works often struggles to simultaneously balance the antibiotics degradation and H2O2 production. Herein, bifunctional TiO2 mesocrystal with oxygen vacancy (meso-TiO2-x) was prepared through a facile pyromellitic diimide assisted hydrothermal process. The well-aligned meso-TiO2-x superstructures with unique oxygen vacancies on the surface collectively facilitated the direct h+ oxidation and oxygen reduction reaction (ORR). The ciprofloxacin degradation through direct h+ oxidation boosted the separation of photogenerated carriers, which enhances the e-participation in ORR, resulting H2O2 production rate up to 904.2 }mol g-1 h-1. This work provides an ingenious strategy of constructing bifunctional catalyst to achieve synergistic antibiotics degradation and H2O2 production without the addition of exogenous reagents. (c) 2025 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.

The development of green and high-performance nanofiltration membranes is of great significance in mitigating the global water crisis. However, conventional nanofiltration membranes are generally constrained by the trade-off between permeability and selectivity, which limits their practical application. In this study, we designed a reactive interlayer based on piperazine-grafted carboxylated cellulose nanofibers, which participates in the interfacial polymerization process to form a mixed nascent layer (MNL) with smaller pore sizes. This intermediate structure further regulated the formation of an ultrathin polyamide layer featuring uniform pore size distribution and a crumpled morphology. Combined with molecular dynamics (MD) simulations, we systematically elucidated the influence of different nascent interlayer structures on the final morphology and chemical composition of the polyamide layer. The resulting membrane exhibits exceptional ion sieving performance, with a Cl-/SO42- selectivity of up to 155.4, and maintains a high water permeance of 43.9 L m-2 h-1 bar-1 while demonstrating effective removal of various micropollutants. This work not only deepens the understanding of the structural evolution mechanism during interfacial polymerization but also provides a new strategy for developing high-performance nanofiltration membranes toward efficient water treatment.

The eco-friendly and cost-effective regulation of interface polymerization (IP) reaction is an effective strategy to enhance the energy efficiency of nanofiltration (NF). In this work, a novel polyamide (PA) NF membrane was prepared by introducing glycerol-doped sugarcane cellulose nanofibers as a biomass composite interlayer. The optimized interlayer could modulate the water-organic interfacial tension and regulate piperazine (PIP) diffusion, thereby enabling a more controlled IP reaction. The optimized membrane (TFC-8) featured a more homogeneous and integrity PA separation layer with the thickness of only 25 nm. Compared to the control membrane, TFC-8 exhibited a lower zeta potential, reduced pore size, a narrower pore size distribution, and a high pure water permeance of 45.78 LMH/bar. Additionally, TFC-8 achieved a high monovalent/divalent anion selectivity of 160.38 in the treatment of dyeing wastewater and showed great potential in the removal of organic micropollutants. Molecular dynamics simulations and interfacial tension confirmed that the composite interlayer greatly improved the tension at the water-organic interface, promoting a more uniform trans-interfacial mass transfer process of PIP. Overall, this work represents a novel eco-friendly modification method for the preparation of homogeneous and structurally intact PA NF membranes for efficient separation of inorganic salts from wastewater.

The highly selective removal of Pb(Ⅱ) from complex wastewater is crucial for effectively treating lead-containing industrial wastewater. Herein, a composite hydrogel adsorbent (LSS-SA) was synthesized by modifying waste Al-rich sludge via free radical polymerization of sodium lignosulfonate (LS) and acrylamide, followed by encapsulation within a sodium alginate (SA) matrix. The LSS-SA possessed a fibrous network morphology and exhibited a 192.70 % increase in specific surface area compared to pure SA. Notably, LSS-SA demonstrated exceptional selectivity for Pb(Ⅱ) against competing divalent metals (Zn(Ⅱ), Cd(Ⅱ), Ni(Ⅱ)), achieving maximum selectivity coefficients of 67.78, 63.60, and 159.94, respectively. The high selectivity for Pb(Ⅱ) was primarily attributed to strong coordination with sulfonic acid groups and amino groups. The adsorbent also demonstrated strong anti-interference capability against co-existing ions, excellent regenerability (above 95.14 %) and low cost ($ 841.36/t). These results, together with dynamic column studies and simulated wastewater tests, collectively demonstrate the potential of LSS-SA as an efficient and sustainable adsorbent for treating actual lead-containing wastewater.

Electrochemical nitrate (NO3 -) reduction to dinitrogen (N2) is a promising approach for environmental remediation but suffers from the sluggish *NO coupling and excessive *H supply on traditional electrocatalysts. Herein, we construct a sulfur-doped zero-valent iron (Fe0@S) aerogel that enables highly selective electrochemical nitrate-to-dinitrogen conversion via *NO→*N2O→N2 path by synchronously regulating *H supply and *NO coupling. Mechanistic studies reveal that the aerogel's 3D porous framework enriches local NO3 - near active sites, while strategic sulfur incorporation can weaken H2O adsorption and tune *NO3 - binding strength, thereby lowering the energy barrier for *NO coupling into *N2O and subsequent reduction to N2. With a flow-through electrolyzer, we achieve near-complete removal of 50 mg/L NO3 - from real surface and ground water with a high N2 selectivity above 90%. This work provides a practical NO3 - remediation method based on non-noble metals and presents a simple strategy for the design of catalyst structure to improve N2 selectivity.

In this work, novel composite multifunctional electrocatalysts, displaying outstanding electrocatalytic capabilities and phenol degradation performance, were successfully synthesized via a facile and controllable electrochemical deposition process, in which nanostructured bimetallic (Co-Ni) molybdates were uniformly deposited onto the surface of stainless steel felt fibers. Co6Ni4Mo@SSF, identified as the superior electrocatalyst with the optimal molar proportion (Co/Ni = 6/4), possessed an amorphous multimetallic structure that was uniformly distributed, offering abundant active sites and excellent structural stability. Notably, Co6Ni4Mo@SSF demonstrated exceptional bifunctional activity toward the HER and OER while enabling efficient phenol degradation during overall water splitting. In KOH electrolyte containing phenol (20 mg L-1), the overpotentials at 100 mA cm-2 were 330.5 mV (HER) and 229.0 mV (OER), with corresponding Tafel slopes of 46.1 and 44.9 mV dec-1, respectively. Both reactions maintained stable operation for 30 h, with performance comparable to that in pure KOH. Moreover, overall water splitting operated stably at 1.789 V for 30 h, while phenol degradation, following first-order kinetics, was nearly completed within 180 min. After 30 h of continuous operation, the Co6Ni4Mo@SSF electrode retained its elemental composition and nanostructured morphology. The remarkable catalytic activity and phenol degradation capability were attributed to the synergistic interactions among the Co, Ni, and Mo active centers in the Co6Ni4Mo@SSF electrode, coupled with the abundance of exposed active sites derived from the distinct morphological reconstruction from nanoparticles to nanosheets during the overall water splitting process. This work offers a novel strategy for developing highly efficient multifunctional electrocatalysts with considerable promise for practical applications in sustainable energy conversion and environmental remediation.

The relaxedly Fe(II)/Fe(III) cycle significantly hinders photo-Fenton activity. Herein, d band engineering was employed to improve the photo-Fenton activity of FeOCl via a simple F-doping strategy. 3%F-FeOCl demonstrated the optimal photo-Fenton performance for 4-chlorophenol (4-CP) degradation, with the pseudo-first-order kinetics constant of 0.09051 min-1, 5.38 times higher than that of pristine FeOCl. Multiple complementary mechanisms underlying the enhanced iron cycle were elucidated. Kelvin probe force microscopy and photoelectrochemical characterization revealed F-doping strengthened the intrinsic built-in electric field of pristine FeOCl by 43.75%, thereby promoting the photogenerated charge carrier separation. Density functional theory calculations further uncovered that F-doping optimized the electronic structure by downshifting the Dband center of Fe (from-1.82 eV to-1.90 eV) and negatively shifting the conduction band (from-0.42 eV to-0.50 eV), which collectively enhanced H2O2 adsorption (from-0.31 eV to-0.99 eV) and facilitated O-O bond cleavage with increased charge transfer (from 0.27 e-to 0.35 e-). These modifications accelerated the Fe2+/Fe3+ redox cycling, as evidenced by the increased Fe2+/Fe3+ ratio after reaction. Radical quenching experiments and electron paramagnetic resonance spectroscopy illuminated that center dot OH and center dot O2-served as the predominant reactive species. Moreover, 3%F-FeOCl exhibited robust photo-Fenton performance within various water matrices. Overall, this work established an available F-doping mediated D-band center strategy for the design of photo-Fenton catalysts.

Rational design of biomass-activated carbon cathodes with engineered hierarchical porosity is a critical scientific challenge. Herein, we exploited waste rice husk as the raw material and employed a dual-etching strategy (H3PO4 pre-ecthing and followed by KHCO3 re-etching) to construct series of N, O-doped biomass-activated carbon P-PBC-X (X = 1, 4, 8) with abundant topological nanochannel structures. The pore structure analysis showed that the H3PO4 pre-ecthing effectively optimized the pore structure distribution of biomass-activated carbon. Cosequently, P-PBC-4 exhibited the optimal electrocatalytic O2 activation performance for TC dgradation with a k value of 0.1322 min(-1), exceeding most reported works. Linear fitting analysis revealed the H2O2 yield was positively correlated (R-2=0.9041) with the micropore area (SMicro), while the mesopore volume (VMeso) favoured TC degradation (R-2=0.8324). DFT calculations show that N doping and edge C-O-C groups effectively lower the energy barrier for *OOH generation, thus facilitating the 2e(-)-ORR process. Our work greatly forward the rational design and fabrication of high-performance biomass-activated carbon cathodes for electrocatalytic O2 activation and antibiotics degradation.

Photocatalytic 1O2 generation has emerged as a promising technology for environmental remediation and organics synthesis. Nevertheless, the efficiency of photocatalytic 1O2 generation via O2 activation through chargetransfer mechanism remains challenging in carbon nitride due to the weak dielectric screening effect. Herein, series of uric acid (UA)-modified ultrathin carbon nitride nanosheets (UCN-x) were fabricated by the simple supramolecular self-assembly process. Comprehensive characterizations revealed that the incorporation of UA pigment would induce purine structure into heptazine skeleton. Photocatalytic experiments showed that the modification of UA greatly enhanced photocatalytic 1O2 generation ability. The optimal UCN-2 exhibited superior photocatalytic degradation of tetracycline (TC) with the normalized TC degradation rate up to 10.03 mgTC gcat-1 min-1, which was 2.1-31.1 times as high as that of reported photocatalysts. What's more, UCN-2 exhibited excellent photocatalytic TC degradation across diverse aqueous conditions, demonstrating significant potential in environmental remediation. Time-dependent density functional theory (TD-DFT) calculation revealed that the doping of UA could trigger the spatial separation of h+/e- distribution, with h+ concentrated in UA pigment and e- concentrated in adjacent heptazine ring. The engineered adjacent redox sites were precisely tailored to align with the charge-transfer mechanism for photocatalytic 1O2 generation. This work established a fundamental framework for designing highly efficient photocatalysts with manipulated O2 activation.

The performance of conventional heterogeneous catalytic ozonation (HCO) is severely impaired in hypersaline wastewater due to the scavenging of hydroxyl radicals (HO•) by chloride ions (Cl⁻). Herein, we fabricate a mechanochemically tailored Cu(I)-rich CuxO/MnOx catalyst to steer ozone activation toward a Cu(III)-mediated non-radical pathway. Ball milling promotes the formation of interfacial Cu-O-Mn linkages, enabling electron transfer from MnOx to Cu sites and stabilizing surface Cu(I). Using oxalate as a model recalcitrant contaminant, the CuxO/MnOx/O3 system achieves 93.2 %-100 % oxalate removal over a pH range of 4.0-9.0 and retains 81.7 % removal at 300 mM Cl-. Multiple lines of evidence confirm that Cu(III), rather than HO•, acts as the dominant oxidant. Notably, this system exhibits oxidative stability owing to continuous Cu(I)/Cu(III) redox cycling, which could be attributed to the electron replenishment to Cu sites from MnOx and O2•⁻ mediated by Cu-O-Mn bonds. Furthermore, when applied to real hypersaline wastewaters with total dissolved solids of 8.1-24.1 g L-1, the CuxO/MnOx membrane catalytic system attains 56.7 %-76.8 % TOC removal, representing a 1.6- to 2.7-fold enhancement over ozonation. This work provides a robust strategy for developing salt-resistant non-radical HCO systems for hypersaline wastewater treatment.

The heat-activated peroxydisulfate (PDS) system exhibits significant potential for removing polyvinyl alcohol (PVA) through polymerization in water treatment. However, excessive chain scission severely limits intermolecular crosslinking and oxidant utilization efficiency during the polymerization process. Herein, we demonstrated that introducing ferric chloride (FeCl3) into the heat/PDS system dramatically enhanced PVA polymerization, achieving 22.2- and 11.5-fold improvements in TOC removal and PDS utilization efficiency, respectively. Mechanistic investigations revealed a dual-regulation mechanism involving Fe(III)-induced intermolecular pre-organization of PVA chains and a shift in the dominant radicals from sulfate radicals (SO4 center dot-) to chlorine radicals (Cl center dot). Fe(III)-mediated pre-organization shortened intermolecular distances, creating a favorable conformation for subsequent crosslinking, while Cl center dot preferentially abstracted hydrogen atoms from PVA rather than cleaving the carbon backbone, thereby suppressing chain scission and promoting polymer growth. As a result, insoluble Fe-coordinated polymeric aggregates with porous, amorphous, and thermally stable characteristics were formed. Furthermore, the system was effective for treating real desizing wastewater containing PVA and exhibited broad applicability to hydroxylated aromatic compounds. Overall, this study provides a feasible strategy for enhancing PVA polymerization in the heat/PDS system by suppressing chain scission and promoting intermolecular crosslinking, offering new insights into improving oxidant utilization and selective polymerization in advanced oxidation processes.

While heteroatom doping is competent to enhance 2e(-)-ORR activity of metal-free carbon catalysts, high-density phosphorus doping remains underexplored due to the large atomic radius of P atom and oxidation tendency. Herein, we propose an innovative strategy using low-cost ammonium polyphosphate and chitosan oligosaccharide as precursors. Phosphorus immobilization via sol-gel assembly followed by pyrolysis-induced carbon rearrangement enabled high-density -POx functionalization on high-curvature carbon spheres (P content > 20 wt%), yielding NBC-xP catalysts (x = 1-3, x represents the amount of APP added). NBC-2P exhibited excellent electrocatalytic performance with 98.56% H2O2 selectivity at 0.4 V and the production rate of 2.43 mol g(-1) h(-1) in a H-cell. Notably, the H2O2 production rate further increased to 14.32 mol g(cat)(-1) h(-1) in a gas diffusion electrode (GDE) flow cell. Density functional theory calculations verified that rational high-density -POx doping significantly reduced the H2O2 formation energy barrier, stabilizing the 2e(-)-ORR pathway. This work revealed the synergistic role of APP-induced structural reconstruction and high-density -POx-mediated electronic modulation in optimizing metal-free carbon electrocatalysts for selective H2O2 electrosynthesis.