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Employing perylene diimide supermolecule (PDI) as metal-free cocatalyst, a novel PDI/g-C

The difficulty in Fe(III)/Fe(II) conversion in the Fe(III)/peroxymonosulfate (PMS) process limits its efficiency and application. Herein, L-cysteine (Cys), a green natural organic ligand with reducing capability, was innovatively introduced into Fe(III)/PMS to construct an excellent Cys/Fe(III)/PMS process. The Cys/Fe(III)/PMS process, at room temperature, can degrade a variety of organic contaminants, including dyes, phenolic compounds, and pharmaceuticals. In subsequent experiments with acid orange 7 (AO7), the AO7 degradation efficiency followed pseudo-first-order kinetic which exhibited an initial “fast stage” and a second “slow stage”. The rate constant values ranged depending on the initial Cys, Fe(III), PMS, and AO7 concentrations, reaction temperature, and pH values. In addition, the presence of Cl−, NO3−, and SO42− had negligible impact while HCO3− and humic acid inhibited the degradation of AO7. Furthermore, radical scavenger experiments and methyl phenyl sulfoxide (PMSO) transformation assay indicated that sulfate radical, hydroxyl radical, and ferryl ion (Fe(IV)) were the dominant reactive species involved in the Cys/Fe(III)/PMS process. Finally, based on the results of gas chromatography-mass spectrometry, several AO7 degradation pathways, including N=N cleavage, hydroxylation, and ring opening were proposed. This study provided a new insight to improve the efficiency of Fe(III)/PMS process by accelerating Fe(III)/Fe(II) cycle with Cys.

The combination of sulfate radical-mediated advanced oxidation process (SA-AOP) and photocatalysis is researched as a highly efficient strategy for pollutant degradation in recent decades. To systematically study the synergistic effect between photocatalysis and peroxymonosulfate (PMS) induced SA-AOP, graphene oxide (GO) coupled graphitic carbon nitride (CN) composites were synthesized as catalyst. About 98% of bisphenol A was decomposed in CNGO/PMS/light system, which was significantly higher than that in CNGO/PMS or CNGO/light system, demonstrating the strong synergistic effect between photocatalysis and SA-AOP. CNGO was deactivated in catalyst/PMS system, but not in catalyst/PMS/light system, showing that the deactivation of CNGO in the presence of sulfate radicals was inhibited by the photocatalysis. The photogenerated electrons may directly reduce the oxidized GO, or react with the oxidative species which may oxidize GO, and thus maintain the activity of CNGO. In addition, the system temperature was elevated due to the light-to-heat conversion on GO. The increased reaction temperature accelerated the degradation reaction due to the improved the charge separation and molecular collision. This work explains the synergy effect between photocatalysis and SA-AOP from different perspectives, and provides a new idea to improve the reusability of carbonaceous catalyst.

The g-C3N4/Y-TiO2 Z-scheme heterojunction photocatalysts were successfully synthesized. Powder X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used for characterization. The photocatalytic activity of the as-prepared samples was investigated via the degradation efficiency of rhodamine B (RhB) under visible-light irradiation, and 20 mg L−1 RhB was completely degraded in 90 min. The results showed that the photocatalytic degradation of RhB conformed to pseudo-first-order kinetic fitting, and the kinetic constants of g-C3N4/Y-TiO2 were 4.27 times higher than those of g-C3N4/TiO2 and 14.18 times higher than those of Y-TiO2, respectively. The enhanced photocatalytic activity of g-C3N4/Y-TiO2 was due to the formation of a Z-scheme heterojunction by Y at the g-C3N4/TiO2 interface. Formation of the Z-scheme heterojunction resulted in the suppression of photo-generated electron–hole pair recombination and the increase of their lifetimes, which was demonstrated by the transient photocurrent response, electrochemical impedance spectroscopy, and the time-resolved photoluminescence spectra. The superoxide radical and photo-generated holes played a dominant role in the photocatalytic degradation process of RhB by g-C3N4/Y-TiO2.

Piezocatalysis is a promising approach for environmental pollutant removal. Monoclinic dibismuth tetraoxide (m-Bi2O4) was first applied to piezocatalyze organics under ultrasonic vibration. The built-in electric field with ultrasonic stress drives the separation of holes and electrons in m-Bi2O4. Its excellent piezocatalytic activity, reusability and chemical stability make m-Bi2O4 a new candidate of piezocatalysis.

Tri(2-chloroisopropyl) phosphate (TCPP), a common organophosphate flame retardant, was frequently detected in the environment and posed threats to human health. In this work, the main component of ilmenite FeTiO

Solar-driven distillation and desalination are promising technologies for large-scale water purification. Internal micro-channels are critical for the performance of a steam generation device in consideration of thermal management and water transportation. Here, we designed novel porous three-dimensional carbon foams (CFs) with unique interconnected channels and rough surfaces via alkali activation of naturally abundant wood. Promoted by the rough surface, the CFs can harvest more than 97% of the energy of the solar spectrum. The hydrophilic interconnected micro-channels of the CFs enhance water transportation and heat localization. Benefiting from these advantages, the highest steam generation efficiency of the CFs reaches 80.1% under 1 kW m−2. In addition, the CFs also show high stability under harsh conditions and high activity in desalination of seawater. With the unique interconnected micro-channels, this porous carbon device offers a scalable, cost-effective and efficient choice for solar steam generation.

Piezocatalysis is a promising approach for environmental pollutant removal. Monoclinic dibismuth tetraoxide (m-Bi

Environment pollution is getting serious and various poisonous contaminants with chemical durability, biotoxicity and bioaccumulation have been widespreadly discovered in municipal wastewaters and surface water. The detection and removal of pollutants show great significance for the protection of human health and other organisms. Due to its distinctive physical and chemical properties, perylene diimide (PDI) has received widespread attention from different research fields, especially in the area of environment. In this review, a comprehensive summary of the development of PDI-based materials in fluorescence detection and advanced oxidation technology for environment was introduced. Firstly, we chiefly presented the recent progress about the synthesis of PDI and PDI-based nanomaterials. Then, their application in fluorescence detection for environment was presented and categorized, principally including the detection of heavy metal ions, harmful anions and organic contaminants in the environment. In addition, the application of PDI and PDI-based materials in different advanced oxidation technologies for environment, such as photocatalysis, photoelectrocatalysis, Fenton and Fenton-like reaction and persulfate activation, was also summarized. At last, the challenges and future prospects of PDI-based materials in environmental applications were discussed. This review focuses on presenting the practical applications of PDI and PDI-based materials as fluorescent probes or catalysts (especially photocatalysts) in the detection of hazardous substances or catalytic elimination of organic contaminants. The contents are aimed at supplying the researchers with a deeper understanding of PDI and PDI-based materials and encouraging their further development in environmental applications.

A novel oxygen-doped g-C

Microplastics (MPs), as emerging contaminants, are posing potential risks to environment, and animal and human health. The ubiquitous presence of MPs in natural ecosystems provides favorable platform to selectively adsorb antibiotic resistant genes (ARGs) and bacteria (ARB) and bacterial assemblages, especially in wastewater which is hotspot for MPs, ARGs and ARB. In this study, the selective capture of intracellular ARGs (iARGs), extracellular ARGs (eARGs), and bacterial assemblages by MPs with different materials (i.e. polyethylene, polyvinylchloride, and polyethylene terephthalate) and sizes (200 μm and 100 μm) was investigated. The results showed that iARGs (i.e. i-TetA, i-TetC, i-TetO, i-sul1), integron-integrase gene (intI1), and eARGs (i.e. e-TetA and e-bla

Sulfate aerosol is a major fraction of haze, playing an important role in aerosol formation and aging processes. In order to understand the mechanism of sulfate formations, the characteristics of sulfur isotope composition were determined during different heterogeneous oxidation reactions of sulfur dioxide. Although NH3 was more beneficial to the formation of sulfate, compared with NOX and O3, 34S tended to enrich the lighter sulfur isotopes in the presence of NH3. Furthermore, in consideration of the potential competitive effects of NOX, O3, and NH3 in the heterogeneous oxidation processes, the contributions of each gas were evaluated via Rayleigh distillation model. Notably, NOX oxidation contributed 67.5±10 % of the whole sulfate production, which is higher than O3 (13.3±10 %), and NH3 oxidation (19.2±10 %) on the basic of the average fractionation factor. The observed δ34S values of sulfate aerosols were negatively correlated with sulfur oxidation ratios, owing to the sulfur isotopic fractionations during the sulfate formation processes. Given the isotope mass balance, the overall δ34Ssulfate approached the δ34Semission as oxidation of SO2 progressed, suggesting that NOX played a major rather than a sole role in the different heterogeneous oxidation processes of SO2.

A novel n-n type inorganic/organic heterojunction of flaky-like BiOCl/PDI photocatalyst was constructed by water bath heating method. Meanwhile, a simple method - secondary self-assembly was used to prepare the BiOCl/PDI with a special band structure. The photocatalytic activities were evaluated by degrading aqueous organic pollutants under visible light (λ > 420 nm). The removal rates of 5 mg L−1 phenol (non-ionic type), methyl orange (MO, anionic type), rhodamine B (RhB, cationic type) and 10 mg L−1 RhB by secondary self-assembly BiOCl/PDI (BiOCl/PDI-2) were 8.0%, 3.4%, 27.8% and 78.9% higher than self-assembly BiOCl/PDI (BiOCl/PDI-1) under visible light (λ > 420 nm). The better photocatalytic activity for BiOCl/PDI-2 was attributed to the optimization of energy-band structures, which arose from different exposed surfaces, narrower interplanar spacing and stronger visible light absorption performance. Under acidic condition, BiOCl/PDI-2 showed a good photocatalytic activity, which was not affected by neutral ionic intensity and had good recycling properties. Moreover, the photocatalytic mechanism was explored by free radical capture test and electron paramagnetic resonance (EPR), and contribution of active species was calculated. The main active species of BiOCl/PDI-2 were ·O2−, 1O2 and h+. Our work may provide a route to design efficient inorganic/organic heterojunctions for organic pollutants degradation.

Visible light photocatalytic nitrogen fixation, as a low-cost and mild technology, needs efforts to explore an economical photocatalyst with high activity and stability. In this study, a metal-free black phosphorus (BP) nanosheets-decorated graphitic carbon nitride nanosheets photocatalyst (BPCNS) has been successfully synthesized. With BP acting as the cocatalyst, BPCNS shows excellent performance in both visible light nitrogen photofixation and pollutant reduction owing to the increased number of excited electrons and enhanced separation efficiency of charge carriers through formation of C P covalent bonds. Besides, the chemical structure of the BPCNS with optimal content of BP remains the same after exposure to air for 30 days or after five cycles of photocatalytic nitrogen fixation, since the occupation of the lone pairs on phosphorus atoms largely improves the chemical stability of BP.

Photocatalysis is considered as a promising method to degrade pollutants with clean and readily available energy source. Great efforts have been devoted to improve solar energy utilization of the photocatalyst. Herein, we report that elemental boron (EB) nanoparticle can act as an advanced bi-functional cocatalyst for photocatalysis with high solar energy utilization. As a photothermal material, EB could convert long-wavelength light energy to heat to increase the reaction temperature and accelerate the photocatalytic reaction. Moreover, the strong electronic interaction between EB and graphitic carbon nitride altered band structure and also suppressed the recombination of charge carriers. Benefiting from these, EB decorated graphitic carbon nitride exhibited dramatic improvement in photocatalytic degradation of sulfamerazine under the simulated sunlight. This work not only reveals the hidden talent of elemental boron as an advanced bi-functional cocatalyst, but also provides an alternative strategy for efficient full-spectrum solar energy conversion.

Sulfate radical-based advanced oxidation process is a promising technology to degrade organic pollutants for water remediation. Photo-activation of peroxymonosulfate (PMS) has received increasing attention. From the aspect of solar energy, the utilization of near-infrared (NIR) light which accounts for about 50% of the solar energy in PMS activation is still challenging. Herein, we designed and synthesized few-layered graphite modified graphitic carbon nitride (GrCN) for whole-spectrum photo-activation of PMS. During the reaction, NIR light was converted to heat on few-layered graphite through photothermal effect to accelerate the chemical reactions via raising the system temperature. In addition to the photothermal effect, few-layered graphite also acted as cocatalyst to alter the band structure and promote the charge separation. Therefore, GrCN exhibited excellent activity in the degradation of bisphenol A with the addition of PMS under illumination. In addition, GrCN presented high reusability in the presence of sulfate radicals under illumination.

Identifying the spatial effects of cobalt cations in cobalt-based heterogeneous catalysts contributes to develop effective peroxymonosulfate (PMS) activators in water treatment. Herein, we investigated typical tetrahedral and octahedral cobalt ions in CoAl2O4 and ZnCo2O4 via an inactive cation substitution strategy towards spinel Co3O4. ZnCo2O4 (0.095 min−1) performs remarkably better than CoAl2O4 (0.007 min−1) for degrading rhodamine B, while non-radical 1O2 is the dominant reactive oxygen species. Then, interface kinetics characterized by systemic electrochemical techniques indicate the feasibility of Co2+/Co3+ transformation and charge transfer resistance at catalyst-electrolyte interface determine intrinsic activity. Octahedral cobalt species exhibit superior intrinsic activities comparing with tetrahedral ones on the removal of several dye and aromatic pollutants. Additionally, flat band potentials of cobalt-based oxides reflecting Fermi level positions is a thermodynamic factor to activate PMS. Our work attempts to further understand spatial occupation-activity relationship of cobalt sites to design efficient PMS activators.

Persulfate (PS) is extensively employed as an oxidant to develop the sulfate radical-based advanced oxidation processes for removing organic pollutants and various PS activation methods have been explored. Iohexol (IOH), as a typical iodinated X-ray contrast media, poses a threat to human health and ecological environment, which is difficult to be removed by conventional treatment methods. In our work, a photocatalytic coupling persulfate system was constructed for efficient IOH degradation. A novel binary photocatalyst of biochar loaded with perylene diimide (PDI/BC, PB) was successfully prepared via a one-pot water bath heating method, which achieved BC acidification and PDI self-assembly simultaneously. Different mass ratios of BC and PDI lead to variance in average particle size, electronegativity, bandgap width and electron/hole separation efficiency. The optimized efficiency of 10 mg/L IOH on PB-9 (PDI:BC = 1:9, w/w) reached 100% in 2 h with 1.5 mM sodium persulfate under visible light irradiation. Based on the results of trapping experiments and electron paramagnetic resonance, holes and hydroxyl radicals were the dominant active species and the free radical chain reaction and mutual conversion reaction of active species occurred. The amide hydrolysis, amine and C-OH oxidation, hydrogen extraction, deiodination and OH addition were observed during the degradation process. Density functional theory calculation was conducted to confirm the free radical attack sites. The findings of this work demonstrate that metal-free supramolecular loaded photocatalyst has the potential for application in the removal of organic pollutants for water remediation.

Platinum modified indium oxide nanorods (Pt/IONRs) were synthesized and applied for photocatalytic degradation of perfluorooctanoic acid (PFOA). IONRs synthesized at 700 °C with 3 wt% Pt exhibited optimal activity in the degradation of PFOA. The improvement of photocatalytic efficiency is mainly ascribed to two aspects: the load of Pt and the rod-like structure, which could promote light harvesting and enhance the separation rate of charge carriers. Besides, the oxygen vacancies on the surface of photocatalyst may accelerate the degradation of PFOA as well. These results suggested that Pt/IONRs could be a promising photocatalyst for PFOA degradation.

Porous oxygen-doped graphitic carbon nitride nanosheets (xSO-g-C 3 N 4 ) were prepared using urea and sodium oleate via thermal copolymerization. The modification of electronic structure, especially the formation of midgap, together with porous nanosheets morphology, promoted light harvesting ability and separation rate of charge carriers, facilitating the visible light photocatalytic activity of xSO-g-C 3 N 4 .

A novel metal-free oxygen doped porous graphitic carbon nitride (OA-g-C3N4) was synthesized by condensation of oxalic acid and urea. The 40% OA-g-C3N4 catalyst can degrade bisphenol A (15 mg L−1) in 240 min with a mineralization rate as high as 56%. The markedly higher visible-light-driven oxidation activity of OA-g-C3N4 is attributed to the porous morphology and unique electrical structure. The porous structure of OA-g-C3N4 provides more active sites for adsorption and degradation of pollutants. Moreover, oxygen atoms in the tri-s-triazine units help to extend sufficient light absorption range up to 700 nm, improve the separation of charge-carriers and alter the position of valence band (VB) and conduction band (CB). The VB edge shifts from 1.95 eV to 2.46 eV due to the incorporation of O atoms, which leads to the change of active species in the photocatalytic reaction. Trapping experiment shows that superoxide radicals play the major role in the photocatalytic degradation of BPA on g-C3N4, while hydroxyl radical is the dominant active species in the photocatalytic degradation process over 40% OA-g-C3N4. This study presents a simple, economical and environment-friendly method to synthesized oxygen doped porous graphitic carbon nitride.

A novel Co3O4/g-C3N4/Bi2O2CO3 (BCCN) photocatalyst with p-n/n-n heterojunction was synthesized through a solvent-thermal method. The degradation efficiency of 20 mg/L iohexol reached 94 % in 60 min (kapp =0.0417 min−1) in BCCN/light/PS system, which was 2.8 and 6.5 times higher than systems of BCCN/light (kapp =0.0150 min−1) and BCCN/PS (kapp =0.0064 min−1). The g-C3N4 addition lowered conduction band of the prepared material to produce superoxide radicals, activate persulfate and further prevent the recombination of photoelectrons and holes. Superoxide radicals and singlet oxygens were dominant radicals for iohexol degradation. Besides, persulfate could act as electron acceptor to enhance efficiency of electron transfer. The interaction between sulfate, superoxide and hydroxyl radicals improved singlet oxygens production. Furthermore, theoretical calculation and liquid chromatography mass spectrometry were performed to analyze degradation pathway of iohexol in the system. Ultimately, the BCCN/light/PS system can provide a new method to degrade organic pollutants in aquatic environments.

A novel PDI/PS/Vis system was constructed and the photocatalytic activity of PDI with various degrees of self-assembly was explored. Perylene diimide (PDI) as photocatalysts possesses excellent charge separation efficiency and the electron injection from the PDI to persulfate (PS) can produce active species more efficiently. With the PDI/PS/Vis system, 5 mg/L bisphenol A (BPA, 50 mL) could be completely removed in 15 min with 0.5 g/L photocatalyst and 1.5 mM PS under visible light (λ>420 nm). Nearly 71.1 % of BPA was mineralized after 1 h degradation. Radical quenching tests and electron paramagnetic resonance (EPR) spectra revealed that h+, ·O2−, ·OH and SO4·- all contributed to organics elimination with radical process. Based on the results of theoretical calculations and toxicity assessment, BPA will eventually be converted into non-toxic ring-opening products. Therefore, the highly efficient PDI/PS/Vis system has great potential for application in water environment remediation.

In this work, magnetic separably barium ferrite nanomaterial (BaFeO) was synthesized via citrate acid assisted sol-gel combustion method. Subsequently, X-ray diffraction (XRD), scanning electron microscopy-energy dispersion spectroscopy (SEM-EDS), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) were applied for its structural, morphological, and electromagnetic characterization. In addition, microwave (MW) absorption and thermal conversion test results indicated the BaFeO had electrothermal rather than magnetothermal conversion capacity. Meanwhile, the synthesized BaFeO showed satisfactory performance in both eliminating and mineralization of a typical triphenylmethane dye, brilliant green (BG), in MW-induced catalytic oxidation (MICO) process without extra oxidant addition. Besides, changes in element valence and content of BaFeO before and after MICO process investigated with XRD, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) showed its relatively stable properties. Furthermore, transition oxygen species involved in MICO process was deduced as lattice oxygen species. Then, the possible degradation pathway of BG was proposed as demethylation, open-loop of triphenylmethane, releasing one ring, formation of the benzene ring and the ultimate mineralization based on the degradation intermediates tentatively identified by gas chromatography mass spectrometry (GC/MS) and liquid chromatography mass spectrometry (LC/MS), respectively. Finally, ecotoxicity analysis by ecological structure activity relationships (ECOSAR) showed that both the acute and chronic toxicity of these intermediates were lower than that of parent BG. These findings are important regarding the development of efficient catalysts in MICO process for degradation of BG analogues in wastewater.

Palladium loaded mesoporous carbon nitride (Pd/MCN) with high adsorption capacity and excellent catalytic hydrodebromination activity was used for removal of tetrabromobisphenol A (TBBPA). The adsorption kinetic of TBBPA on Pd/MCN-x followed the pseudo-second-order kinetic model and the adsorption isotherm could be described by Langmuir adsorption model. The pore structure and surface functional groups of Pd/MCN-x could be optimized by calcination at different temperatures. The Pd/MCN-900 catalyst exhibited the highest TBBPA adsorption capacity of 242.1 mg/g, which was 2⿿10 times larger than previous values achieved by other researchers. Both hydrophobic interaction and Ͽ-Ͽ interaction were responsible for the adsorption and the solution pH and coexisting ions had little influence on the adsorption. The catalytic hydrodebromination results showed that the TBBPA could be was completely debrominated to BPA over Pd/MCN-x and the catalytic activity of Pd/MCN-x was positive correlated to the adsorption behavior of TBBPA. The high adsorption capacity and catalytic hydrodebromination activity of Pd/MCN-x made it suitable for the treatment of TBBPA.

CeO2-doped indium oxide photocatalysts (xCeO2/In2O3) with various CeO2 doping amounts were synthesized and systematically characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis spectra, photoluminescence spectroscopy (PL) and photocurrent measurements. The as-obtained xCeO2/In2O3 photocatalysts were used in photocatalytic degradation of PFOA for the first time and much higher photocatalytic activity of xCeO2/In2O3 than CeO2 and In2O3 was obtained under UV light irradiation. The excellent photocatalytic activity of 0.86% CeO2/In2O3 could be mainly derived from effective inhibition of recombination of photo-induced electron-holes caused by the charge transfer between CeO2 and In2O3. Moreover, the 0.86% CeO2/In2O3 catalyst showed excellent photocatalytic stability in cycling runs for the photocatalytic degradation of PFOA, providing a great potential of CeO2/In2O3 catalysts for PFOA treatment.

Photocatalytic nitrogen fixation is considered as a promising candidate for artificial green NH3 production. Searching an environment-friendly photocatalyst with high activity is necessary for the development of photocatalytic nitrogen fixation. Here, a metal-free semi-crystalline g-C3N4 with midgap states (CNV-550) was prepared by heating melamine in a sealed environment. The CNV-550 presented a photocatalytic nitrogen fixation rate of 91.6 μmol L−1 h−1 under visible light without any sacrificial reagent, which was 14.8 times as high as that of pristine g-C3N4. The midgap states from the interaction between g-C3N4 and melem extended the light response range of CNV-550 to 700 nm. The recombination of photogenerated electron-hole pairs was inhibited by the midgap states and the order-disorder interfaces of the semi-crystalline g-C3N4; accordingly, the apparent quantum efficiency reached 1.89% at 420 nm. This work not only present a metal-free high efficient photocatalyst for nitrogen fixation, but also introduces a new method to modify g-C3N4 material by controlling the reaction pressure.

Iohexol (IOH), as a typical iodinated X-ray contrast media (ICMs) with potential threat to human health, is difficult to be removed with the conventional wastewater treatment methods. In this work, new boron nitride coupled Bi2MoO6 layered microspheres (BN/Bi2MoO6) composites were applied to remove IOH from water via photocatalytic degradation. The degradation constant kapp of IOH over 3.5 wt% BN/Bi2MoO6 was 0.016 min−1, which was 3.2 times that of Bi2MoO6 (0.005 min−1). The degradation rate of IOH on 3.5 wt% BN/Bi2MoO6 reached 92% in 150 min. The enhanced photocatalytic activity of BN/Bi2MoO6 can be attributed to the heterojunction between BN and Bi2MoO6. The matched type-I band alignment heterojunction of two semiconductors prominently improved the charge separation. Based on the trapping experiments, holes and superoxide radicals were proved to be the main active species for photocatalytic IOH degradation. Besides, the degradation products of IOH were analyzed by LC–HRMS and the possible degradation mechanism of IOH was also proposed in this work.

The utilization of long-wave light (1000–2500 nm) in the solar spectrum is a difficulty in photocatalysis. Based on the Arrhenius equation, the activated carbon (AC)/graphitic carbon nitride (CN) composites were designed for photothermal-assisted photocatalytic water treatment. The short-wave solar energy can be converted to chemical energy on CN, and the long-wave solar energy to thermal energy by AC. The energetics and the interfacial charge transfer of activated carbon (AC)/graphitic carbon nitride (CN) composites (ACCN) were improved owing to the π bond between AC and CN. The excellent light absorption capacity (over 80%) led to higher photocatalytic reaction temperature due to the photothermal effect. The higher temperature accelerated the photocatalytic reaction and facilitates the charge transfer on ACCN. Hence, the optimal ACCN sample with good balance between photothermal and photocatalytic property could degrade 98% of sulfamerazine under simulated solar irradiation in 60 min. This work not only developed efficient and low-cost (~$1/kg) carbon-based photocatalysts with ultrahigh solar utilization, but also discussed the mechanism of photothermal effect on photocatalytic reaction.

A facial hydrothermal method is applied to synthesize bismuth subcarbonate (Bi2O2CO3, BOC) with controllable defect density (named BOC- X) using sodium bismuthate (NaBiO3) and graphitic carbon nitride (GCN) as precursors. The defects of BOC- X may originate from the extremely slow decomposition of GCN during the hydrothermal process. The BOC- X with optimal defect density shows a photocatalytic nitrogen fixation amount of 957 μmol L-1 under simulated sunlight irradiation within 4 h, which is 9.4 times as high as that of pristine BOC. This superior photocatalytic performance of BOC- X is attributed to the surface defect sites. These defects in BOC- X contribute to a defect level in the forbidden band, which extends the light-harvest region of the photocatalyst from the ultraviolet to the visible-light region. Besides, surface defects prevent electron-hole recombination by accommodating photogenerated electrons in the defect level to promote the separation efficiency of charge carrier pairs. This work not only demonstrates a novel and scalable strategy to synthesize defective Bi2O2CO3 but also presents a new perspective for the synthesis of photocatalysts with controllable defect density.

Perflourooctane sulfonate (PFOS) and perflourooctanoate (PFOA) in aqueous environment have attracted considerable attention. The adsorption of PFOS and PFOA on polyaniline nanotubes (PANTs) from water was studied. The results of adsorption kinetics showed that the adsorption equilibrium of PFOS and PFOA on PANTs could be achieved in 48 h and the experimental data could be fitted well by pseudo-second-order model, reflecting of a chemical controlled adsorption. The adsorption isotherms of PFOS and PFOA on PANTs fitted well to the Langmuir model, suggesting the adsorption behavior was monolayer adsorption and the maximum adsorption amount were 1651 mg/g and 1100 mg/g for PFOS and PFOA on polyaniline emeraldine salt nanotubes (PASNTs), respectively. Thermodynamic results indicated that the adsorption process of PFOS and PFOA by PANTs was endothermic. The electrostatic attraction played an important role in the adsorption of PFOS and PFOA on PANTs and other forces such as hydrophobic interaction might be also involved.

Graphitic carbon nitride (g-C3N4) nanosheets were synthesized by exfoliating bulk g-C3N4 with a thermal treatment under H2 for the first time. The g-C3N4 nanosheets exhibited a 2D structure with a thickness of 2 nm, a high surface area and a low recombination rate of photogenerated electron–hole pairs, enhancing the visible light photocatalytic activity.