Photocatalytic Reaction Kinetics Research Articles

Gas-phase self-assembly: Converting 2D graphitic carbon nitride into 1D nanotubes for improved photocatalytic tetracycline degradation

Achieving precise control and optimization of structure and composition is paramount for advancing photocatalyst performance. In this study, we successfully synthesized nitrogen-defect and boron-doped one-dimensional g-C3N4 nanotubes (BCNNT) with a tube diameter of approximately 100 nm using a one-step gas-phase self-assembly strategy. Intriguingly, the introduction of boric acid induced a transformation from a two-dimensional g-C3N4 structure to a one-dimensional tubular form. The physicochemical properties and photocatalytic performance of BCNNT were found to be influenced by the quantity of boric acid employed. The as-synthesized BCNNT exhibited notable advantages, including enhanced visible light absorption, a 0.1 eV reduction in the band gap, 5.1 times increase in photocurrent density, effective suppression of electron-hole recombination, and significant improvement in mass transfer compared to pure g-C3N4. Consequently, the first-order kinetic constant of BCNNT increased by 73.7 %, resulting in nearly 80 % degradation of tetracycline (TC) within half an hour. The boron doping played a crucial role in reducing the surface energy required for nanotube formation during synthesis, a key factor in their structural development. Both density functional theory (DFT) calculations and experimental studies confirmed that the Lewis acid site B enhanced tetracycline adsorption, while nitrogen-deficient sites suppressed electron-hole recombination, thus accelerating photocatalytic degradation rate. This research provides a novel perspective on fabricating tubular g-C3N4 structures and compositions, offering insights for improving the kinetics of photocatalytic reactions.

A novel nickel-doped photoactive nanocomposite materials for the application of wastewater treatment

We have reported an efficient and novel nanocomposite structure of nickel (0.5 %, 1.0 %, 1.5 %, 2.0 % and 2.5 %) doped Fe3O4@rGO which is prepared by a simple chemical co-precipitation technique for degradation of methylene blue. In the current study, reduced graphene oxide (rGO) is chosen as the electron mediator for NiFe3O4/rGO nanocomposite catalyst to construct a binary photocatalytic system. The analysis of structural and optical properties supports their nano size, formation of nanocomposite material, doping of nickel ions into the characteristic inverse spinel cubic structure of Fe3O4 and the existence of synergistic effect between NiFe3O4 and rGO. Methylene blue was considered as a model dye during the investigation of the Photocatalytic activity of NiFe3O4/rGO. From the kinetic measurements, the reaction rate was predicted to play a key role in the process of degradation. This discussion also highlights the absorption peak extension towards the visible region and the energy band gap value decreases with increasing the nickel dopant concentration in novel NiFe3O4/rGO nanocomposite material. Transition metal doping significantly enhances the degradation efficiency and reduces the recombination rate of charge carriers which makes the NiFe3O4/rGO nanocomposite material a potential candidate for the degradation of methylene blue from wastewater. As indicated by all the nanocomposites, photocatalytic activity was higher than the pure Fe3O4 photocatalyst, and the highest photodegradation of 96.3 % MB within 30 min irradiation under visible light was shown by the 2.0 % of nickel-doped Fe3O4@rGO. In addition, the study examined the photodegradation process and photocatalytic reaction kinetics of MB.

A new Keggin-type polyoxometallate-based bifunctional catalyst for trace detection and pH-universal photodegradation of phenol

The widespread application of phenolic substances in the field of food, medicine and industry, is harmful to the environment and human health. Therefore, it is very important to develop a convenient and effective method to detect and degrade phenolic compounds. Herein, we report a new keggin-type polyoxometallate-based metal-organic complex self-assembled under solvothermal condition, {[Cu(dap)(3-PA)]4(SiW12O40)(H2O)2}·2H2O (1, dap = 1,2-diaminopropane, 3-HPA = 3-pyridineacrylic acid). 1 shows an interesting 1D ladder-like structure. As a bifunctional catalyst, 1 can be employed as a colorimetric sensor toward phenol with the relatively low detection limit (LOD) of 0.36 µmol/L (S/N = 3) in the wide range (0.001–0.1 mmol/L). The title colorimetric sensor is applied to determine phenol in various water environment with good recoveries ranging from 95%–105%. In addition, 1 also exhibits excellent photocatalytic degradation toward phenol under visible light with the highest removal efficiency at 96% for 100 min and wide pH universality. The selectivity, stability and reliability of the detection of 1 towards phenol, as well as the detection for 4-chlorophenol, o-cresol, 4-nitrophenol and phloroglucinol were studied. Furthermore, the photocatalytic reaction kinetics and the mechanisms of photodegradation of phenol were also investigated in detail.

ZnO QDs/GO/g-C3N4 Preparation and Photocatalytic Properties of Composites.

Using an ultrasound-assisted chemical technique, ZnO quantum dot and ZnO composites were created. The optical characteristics and structural details of these composites were examined using TEM, XRD, XPS, FT-IR, UV-vis, and BET. The results revealed that both the ZnO quantum dot composite and ZnO composite exhibited outstanding optical properties, making them suitable for photocatalytic reactions. In order to analyze the photocatalytic performance, a degradation experiment was conducted using Rhodamine B solution as the simulation dye wastewater. The experiment demonstrated that the degradation of Rhodamine B followed the first-order reaction kinetics equation when combined with the photocatalytic reaction kinetics. Moreover, through cyclic stability testing, it was determined that the ZnO QDs-GO-g-C3N4 composite sample showed good stability and could be reused. The degradation rates of Rhodamine B solution using ZnO-GO-g-C3N4 and ZnO QDs-GO-g-C3N4 reached 95.25% and 97.16%, respectively. Furthermore, free-radical-trapping experiments confirmed that ·O2- was the main active species in the catalytic system and its photocatalytic mechanism was elucidated. The photocatalytic oxidation of ZnO quantum dots in this study has important reference value and provides a new idea for the subsequent research.

Interfacial self-assembled dual-functional nanocomposite films for SERS monitoring of visible-light photocatalytic degradation of organic dye pollutants

Photocatalytic degradation by visible-light responsive photocatalysts is an efficient strategy to treat organic dye pollutants and monitoring of the photocatalytic reaction mechanisms and kinetics is important to the design of high-performance photocatalysts. Herein, a dual-functional graphitic carbon nitride/gold nanoparticles (g-C3N4/AuNPs) nanocomposite film is introduced to monitor the photocatalytic reactions by surface-enhanced Raman scattering (SERS) while degrading organic dyes photocatalytically. The nanocomposite film fabricated by two-step interfacial self-assembly consists of orderly arranged g-C3N4 film anchored on a closely packed AuNPs monolayer film. The nanoplatform has excellent SERS characteristics such as a rhodamine 6G (R6G) detection limit of 8.8 × 10−10 M, and good SERS detection uniformity with a relative standard deviation (RSD) of 9.62%, which is crucial to quantitative determination and accurate monitoring of the photocatalytic reactions. The nanoplatform is employed in visible-light photocatalytic degradation of organic dyes including R6G, methylene blue, acid orange II, and acid orange 74. The reactions follow the pseudo-first-order kinetics as revealed by SERS and the photocatalytic degradation mechanism is postulated to be the promoted charge separation. The results reveal a high-performance dual-functional nanoplatform suitable for visible-light photocatalytic degradation of organic dye pollutants and SERS monitoring of the reactions.

A pyridine-based conjugated imprinted polymer as an adsorptive photocatalyst for efficient removal of aqueous Cr(VI).

Herein, a designed pyridine-based conjugated imprinted polymer (CIP) was constructed by introducing 4-vinylpyridine (4-VP) via an in situ copolymerization reaction. In addition to the good adsorption performance of Cr(VI), this polymer also showed high efficiency in reducing Cr(VI) in water by photocatalysis. The ingenious design of the polymer not only furnished insight into the enhanced photocatalytic reaction kinetics but also provided a new route for the modification of the molecular skeleton of the conjugated polymer photocatalyst.

Inactivation of SARS-CoV-2 and Other Human Coronaviruses Aided by Photocatalytic One-Dimensional Titania Nanotube Films as a Self-Disinfecting Surface.

SARS-CoV-2 and its variants that continue to emerge have necessitated the implementation of effective disinfection strategies. Developing self-disinfecting surfaces can be a potential route for reducing fomite transmissions of infectious viruses. We show the effectiveness of TiO2 nanotubes (T_NTs) on photocatalytic inactivation of human coronavirus, HCoV-OC43, as well as SARS-CoV-2. T_NTs were synthesized by the anodization process, and their impact on photocatalytic inactivation was evaluated by the detection of residual viral genome copies (quantitative real-time quantitative reverse transcription polymerase chain reaction) and infectious viruses (infectivity assays). T_NTs with different structural morphologies, wall thicknesses, diameters, and lengths were prepared by varying the time and applied potential during anodization. The virucidal efficacy was tested under different UV-C exposure times to understand the photocatalytic reaction's kinetics. We showed that the T_NT presence boosts the inactivation process and demonstrated complete inactivation of SARS-CoV-2 as well as HCoV-OC43 within 30 s of UV-C illumination. The remarkable cyclic stability of these T_NTs was revealed through a reusability experiment. The spectroscopic and electrochemical analyses have been reported to correlate and quantify the effects of the physical features of T_NT with photoactivity. We anticipate that the proposed one-dimensional T_NT will be applicable for studying the surface inactivation of other coronaviruses including SARS-CoV-2 variants due to similarities in their genomic structure.

Cooperative Coupling of H2 O2 Production and Organic Synthesis over a Floatable Polystyrene-Sphere-Supported TiO2 /Bi2 O3 S-Scheme Photocatalyst.

Cooperative coupling of photocatalytic H2 O2 production with organic synthesis has an expansive perspective in converting solar energy into storable chemical energy. However, traditional powder photocatalysts suffer from severe agglomeration, limited light absorption, poor gas reactant accessibility, and reusable difficulty, which greatly hinders their large-scale application. Herein, floatable composite photocatalysts are synthesized by immobilizing hydrophobic TiO2 and Bi2 O3 on lightweight polystyrene (PS) spheres via hydrothermal and photodeposition methods. The floatable photocatalysts are not only solar transparent, but also upgrade the contact between reactants and photocatalysts. Thus, the floatable step-scheme (S-scheme) TiO2 /Bi2 O3 photocatalyst exhibits a drastically enhanced H2 O2 yield of 1.15mm h-1 and decent furfuryl alcohol conversion to furoic acid synchronously. Furthermore, the S-scheme mechanism and dynamics are systematically investigated by in situ irradiated X-ray photoelectron spectroscopy and femtosecond transient absorption spectrum analyses. In situ Fourier transform infrared spectroscopy and density functional theory calculations reveal the mechanism of furoic acid evolution. The ingenious design of floatable photocatalysts not only furnishes insight into maximizing photocatalytic reaction kinetics but also provides a new route for highly efficient heterogeneous catalysis.

Visible-light-driven CQDs/TiO2 photocatalytic simultaneous removal of Cr(VI) and organics: Cooperative reaction, kinetics and mechanism

CQDs/TiO2 was synthesized with a coprecipitation method and characterized by XRD, SEM, TEM/HRTEM, BET, XPS, UV–Vis DRS and I-t curve technologies. UV–Vis DRS displayed that absorption spectrum of CQDs/TiO2 enlarged to visible light zone, suggesting that CQDs/TiO2 can be irradiated by visible light. I-t curve showed that photocurrent of CQDs/TiO2 was higher than that of bare TiO2, revealing that the doping of CQDs accelerated the transfer of photoelectrons and restrained the recombination of photoinduced carriers. Simultaneous removal of Cr(VI) and organics with CQDs/TiO2 photocatalytic reaction was investigated and factors were optimized, and almost all Cr(VI) and organics were removed under the optimum conditions. Experimental results displayed that there was a distinct cooperation removal effect between Cr(VI) and organics in CQDs/TiO2 photocatalytic reaction. XPS analysis proved that Cr(VI) was reduced to Cr(III) in situ on CQDs/TiO2 surface. There were e−, h+,·OH and ·O2− active species which were detected with DMPO in ESR test during CQDs/TiO2 photocatalytic reaction, and scavenger experiment proved that e− and h+ were the substantial reactants for Cr(VI) and organics, respectively. The pathway of photocatalytic simultaneous removal of Cr(VI) and organics underwent four steps: adsorption of Cr(VI) and organics on CQDs/TiO2 surface; production of photo electrons and holes in visible light; reduction of Cr(VI) and oxidation of organics; desorption of Cr(III) and intermediates. Photocatalytic reaction kinetics of Cr(VI) and organics were both confirmed to pseudo first-order reaction. Life span and small scale real application tests both demonstrated that CQDs/TiO2 had a potential application to wastewater containing Cr(VI) and organics.

Facile sonochemical preparation of La2Cu2O5 nanostructures, characterization, the evaluation of performance, mechanism, and kinetics of photocatalytic reactions for the removal of toxic pollutants

Designing and simulating an effective photocatalytic material having a suitable bandgap to degrade organic pollutants is essential for environmental remediation. This paper describes the development of a class of nanostructure, La2Cu2O5, for photocatalytic decomposition of various types of organic pollutants under UV and visible lights. La2Cu2O5 nanostructures were synthesized by a rapid and environmentally friendly sonochemical technique for the first time. The impacts of molar ratio of precursors, calcination temperature, power, and time of sonication were scrutinized for the synthesis of La2Cu2O5 nanostructures with relevant attributes in terms of purity, particle size, and morphology. The bandgap of these nanostructures was calculated at 3.25 eV, making them profitable for contaminant degradation in the UV region. The photocatalytic activity of the desired La2Cu2O5 was examined for photodegradation of multiple pollutants, such as thymol blue, acid black, methyl violet, rhodamine B, phenol red, malachite green, acid Yellow, and erythrosine for the first time. The La2Cu2O5 nanocatalyst revealed premium performance over the degradation of the mentioned pollutants. La2Cu2O5 was capable of degrading the acid black contaminant better (80.1%). The highest photocatalytic efficiency was obtained at a greater rate constant reaction (k = 0.01332 min−1).

One-step preparation of RGO/Fe3O4\u2013FeVO4 nanocomposites as highly effective photocatalysts under natural sunlight illumination

The study used a one-step hydrothermal method to prepare Fe3O4–FeVO4 and xRGO/Fe3O4–FeVO4 nanocomposites. XRD, TEM, EDS, XPS, DRS, and PL techniques were used to examine the structurally and morphologically properties of the prepared samples. The XRD results appeared that the Fe3O4–FeVO4 has a triclinic crystal structure. Under hydrothermal treatment, (GO) was effectively reduced to (RGO) as illustrated by XRD and XPS results. UV–Vis analysis revealed that the addition of RGO enhanced the absorption in the visible region and narrowed the band gap energy. The photoactivities of the prepared samples were evaluated by degrading methylene blue (MB), phenol and brilliant green under sunlight illumination. As indicated by all the nanocomposites, photocatalytic activity was higher than the pure Fe3O4–FeVO4 photocatalyst, and the highest photodegradation efficiency of MB and phenol was shown by the 10%RGO/Fe3O4–FeVO4. In addition, the study examined the mineralization (TOC), photodegradation process, and photocatalytic reaction kinetics of MB and phenol.

Green fabrication of graphene quantum dots from cotton with CaSiO3 nanostructure and enhanced photocatalytic performance for water treatment

Perovskite nanostructures have become one of the most alluring classes of materials because of their structure and properties, which have revolutionized many areas of electronics, optoelectronics, and photonics. In this research, CaSiO3 nanostructures have been prepared by hydrothermal synthesis as profitable and light-active materials for photocatalytic activities. The photocatalytic procedure is an eco-friendly method, which is recognized as an effective alternative for the degradation of multiple hazardous materials. In this regard, photocatalytic properties of oxide perovskite have been developed by effective incorporation of CaSiO3 nanostructures with graphene quantum dots (GQDs) under facile green low-cost hydrothermal conditions. The impact of two factors, including diverse varieties of surfactants and concentration of GQDs, was surveyed through XRD, FESEM images, and diffuse reflectance spectroscopy (DRS) on purity, structure, and photocatalytic performance. The results demonstrated that the CaSiO3/GQDs in high-level concentration showed higher visible-light photocatalytic activity. Besides, the kinetics of photocatalytic reactions was investigated, and the outcomes showed that higher photocatalytic performance possessed a higher reaction rate coefficient.

Role of NiO Nanoparticles in Enhancing Structure Properties of TiO2 and Its Applications in Photodegradation and Hydrogen Evolution.

Pure and modified mesoporous TiO2 nanoparticles with different loadings of NiO (3–20.0 wt %) were prepared through the surfactant-assisted sol–gel approach with the use of cetyltrimethylammonium bromide as a template. The optical and structural properties of different samples were examined using N2 adsorption–desorption analysis, energy-dispersive spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV–vis spectroscopy, Fourier transform infrared spectroscopy, and photoluminescence (PL) spectroscopy. X-ray diffraction results confirmed the insertion of Ni2+ into the lattice of TiO2, and the crystallite size reduced remarkably after the addition of NiO. The diffuse reflectance spectroscopy spectra displayed obvious red shift in the absorption edges, and new absorption bands appeared in the visible region when NiO was added, which indicates the formation of surface defects and oxygen vacancies. The optical band gap of TiO2 reduced sharply when the contents of NiO were increased. The increase in the surface defects as well as oxygen vacancies were examined using PL spectroscopy. The photocatalytic performance of the as-synthesized samples was investigated over photodegradation of brilliant green (BG) and phenol and hydrogen generation under visible light. 10% NiO/TiO2 exhibited the highest photocatalytic efficiency. The photocatalytic activity was improved due to the creation of a p–n junction at the interface of NiO/TiO2, which efficiently promotes the separation of photogenerated electron/hole pairs and consequently enhances its photodegradation activity. According to the photocatalytic activity results, NiO contents were considered one of the most important factors affecting the photodegradation of BG and phenol and H2 evolution. Also, we discussed the mechanism of photodegradation, mineralization (total organic carbon), and photocatalytic reaction kinetics of BG and phenol.

Evaluation of photodegradation performance by paper microzones

Currently, the performance evaluation of catalysts usually requires expensive instruments. Hence, it is imperative to develop an alternative, green and sustainable method to investigate the photocatalytic reaction processes. Herein, the variation of degradation performance of different wastewaters with different dosage of P25 TiO2 was evaluated to verify the reliability of the paper microzones method (PMZs). The optimum P25 TiO2 dosage of 1 g/L for the degradation of methylene blue (MB) (UV light for 6 mins) and 0.5 g/L for the degradation of fuchsin basic (FB) (UV light for 5 mins) was obtained by the PMZs method. For the photocatalytic degradation of trivalent iron ion complexed salicylic acid (Fe(III)-SA) solution, the R2 values of 0.904 and 0.801 were obtained for the photocatalytic reaction kinetics by PMZs and spectrophotometry, respectively, which again indicated the high reliability of PMZs. The accuracy of the results obtained by PMZs method relative to the spectrophotometric method ranged from 68.80% to 87.54% when degrading MB, FB, mixture of MB and FB, and Fe(III)-SA by P25 TiO2. Therefore, the PMZs method is all in line with the requirements of low-carbon environmental protection and green chemistry, and has broad application prospects in the future.

Kinetic comparison of photocatalysis with H2O2-free photo-Fenton process on BiVO4 and the effective antibiotic degradation

In order to eliminate the serious environment pollution and the super bacteria generation caused by antibiotics discharge, it is an urgently challenging task for effective degradation of antibiotics. Many advanced oxidation technologies including Fenton and photocatalytic reactions have been adopted to face with the challenge of this issue. Herein, we developed a H2O2-free photo-Fenton process using BiVO4 as a light absorbing semiconductor with the addition of Fe3+ to degrade antibiotic under a 300 W Xenon lamp and further comparably investigated the kinetics of H2O2-free photo-Fenton and photocatalytic reactions to degrade rhodamine B (Rh B) and rhodamine 6G (Rh 6G). The corresponding reaction mechanism was proposed based on detailed experiments and data analysis. Subsequently using norfloxacin (NOR) as a model, the H2O2-free photo-Fenton reactions were adopted to evaluate the effectiveness of antibiotic degradation with the optimized conditions of pH = 3.0 and the Fe3+ concentration of 100 mg/L. The results displayed that the H2O2-free photo-Fenton reaction on BiVO4 conformed to pseudo-first-order kinetics and exhibited excellent antibiotic removing performance, the degradation ratio of NOR reached 96% within 1 h. While its photocatalytic cousin abided by pseudo-zero-order kinetics and its degradation ratio was only 25% with the absence of Fe3+ under the same conditions. It is anticipated that this study can deepen the understanding of mechanism and kinetics between photo-Fenton with photocatalytic reactions on the same catalyst and the expansion of H2O2-free photo-Fenton reactions on other semiconductors has great potential in the treatment of wastewater containing various antibiotics.

Synthesis of New Antibiotics Derivatives by the Photocatalytic Method: A Screening Research

The aim of our study was to assess the possibility of using the photocatalytic process conducted in the presence of TiO2 to obtain new stable derivatives of antibacterial drugs. The possibility of introducing hydroxyl, chlorine, or bromide groups into antibiotics molecules was investigated. The experiments were conducted in aqueous solutions in the presence of TiO2-P25 as a photocatalyst, Cl− and Br− ions, and antibiotics belonging to eight different chemical classes. All experiments were initiated by UVa radiation. The kinetics of photocatalytic reactions and their quantum yield were determined, and the stable products were identified. All of the antibiotics used in the experiments underwent a photocatalytic transformation, and the quantum yields were in the range from 0.63 to 22.3%. The presence of Br− or FeCl3 significantly increased the efficiency of the photocatalytic process performed in the presence of TiO2, although Br− ion also acted as an inhibitor. Potentially biologically active chlorine derivatives from Trimethoprim, Metronidazole, Chloramphenicol, and bromine derivatives from Trimethoprim, Amoxicillin were obtained under experimental conditions. The potentially inactive halogen derivatives of Sulfamethoxazole and hydroxyl derivatives described in the literature were also identified.

Intermolecular interactions, photocatalysis and THz-TDS interrelationships for lanthanide phosphine oxide complexes based on {PW12}

A series of rare earth complexes containing (α-PW12O40)3- and PO ligand are synthesized by water bath in 70 °C, [Ln(OPPh3)4(H2O)3](PW12O40)·4CH3CN (Ln = La, Pr, Nd, Sm, Gd, Tb, Ho 1–7) (OPPh3 = Triphenylphosphine oxide, {PW12} = phosphotungstic acid). The precise structures are confirmed by X-ray single crystal diffraction and the result shows all complexes are isostructural. Complexes 1–7 are fully characterized by PXRD, FT-IR, TGA, UV diffuse reflectance spectra and terahertz time-domain spectroscopy (THz-TDS). Complex 3 exhibits the highest photocatalytic degradation efficiency for methylene blue (MB) in this series of complexes. The experimental results showed that the photodegradation efficiency can remain constant at the level of 95% after five consecutive cycles. The photocatalytic reaction kinetics and mechanism of complexes were investigated. Additionally, complexes also exhibit photocatalytic hydrogen evolution activity. THz-TDS was used to characterize the complexes and its raw materials, the characteristic peaks of OPPh3 (broad peak at 1.20 THz) and phosphotungstic acid (sharp peaks at 0.23, 0.32 THz) were obtained.

Preparation of highly efficient sunlight driven photodegradation of some organic pollutants and H2 evolution over rGO/FeVO4 nanocomposites

FeVO4 and rGO/FeVO4 nanocomposites were synthesized by one-step hydrothermal method. The structural and morphological properties of the prepared samples were investigated by XRD, TEM, EDS, XPS, FTIR, Raman, UV–Vis DRS and PL techniques. XRD, XPS and Raman techniques displayed that graphene oxide (GO) was successfully reduced to reduced graphene oxide (rGO) under hydrothermal conditions. Also, the addition of rGO enhanced the visible light absorption, oxygen vacancies, phase transformation of FeVO4 from triclinic to monoclinic phase at high amount of rGO and reduced the band gap energy of FeVO4. The photoactivity of the synthesis catalysts was investigated for the photodegradation of Malachite green, phenol, Methylene blue and Rhodamine B under natural sunlight. Also, the catalysts were applied in H2 evolution from water splitting. The results showed that, the rGO amount was proven to be a crucial factor affecting the structural properties and photocatalytic performance of FeVO4. The mineralization (TOC), photodegradation mechanism and photocatalytic reaction kinetics were discussed.

Granular Polymeric Carbon Nitride with Carbon Vacancies for Enhanced Photocatalytic Hydrogen Evolution

Considering the high charge recombination rate, low optical adsorption intensity and limited active sites greatly constrict the solar‐to‐chemical conversion efficiency of polymer carbon nitride. Herein, a facile approach is reported to produce defected polymeric carbon nitride (PCN) with abundant granular bulks with fractured boundaries by thermal reduction treatment in CO atmosphere. The photocatalytic hydrogen evolution over defected PCN exhibits a rate of 3281.2 μmol g−1 h−1, 3.5 times higher than the pristine, which is most possibly ascribed to the following factors. The unique defected and porous structure not only provides higher specific surface area, more exposed active edges, abundant charge separation sites, and active centers for hydrogen generation but also is beneficial to rapid mass and charge transfer, interior diffusing of incident light, and shortening carrier transport length, thus enhancing the optical adsorption and accelerating the photocatalytic reaction kinetics. Furthermore, the electron delocalization at carbon vacancies sites on one hand facilitates the separation rate of electron–hole pairs and prolonged the carrier lifetime; on the other hand, the electronic polarization caused by C atoms loss helps increasing the affinity between catalyst and substrate reactant. Moreover, the higher electron donor density and lower conduction band minimum (CBM) potential further enhance the reduction capacity for H2 evolution.

Integrating modeling and experimental method for narrowing the optimum phase composition in P25 photocatalyst for typical aromatic pollutants degradation

• The optimum anatase/rutile ratio for typical pollutants was facilely quantified. • The optimal W R of the six pollutants were in a narrow interval of 34.7%–38.4%. • The k depends on energy gap, photoluminescence intensity, and their interaction. • The k of different materials has little correlation with the BET area and groups. The apparent rate constant k of the photocatalytic reaction of typical aromatic pollutants, i.e., dyestuff (rhodamine B [RhB]), phenol (bisphenol A [BPA]), organic chloride (4-chlorophenol [4-CP]), drug (carbamazepine [CBZ]), antibiotics (tetracycline [TC]), and endocrine contaminants (dimethyl phthalate [DMP]), with TiO 2 at different ratios of rutile (W R ) was experimentally obtained. The modelling results between k and W R show that the optimal W R of the six pollutants were in a narrow interval of [0.347, 0.384] by LogNormal model. The two-factor interaction (2FI) and Linear model between the kinetic k value and the photocatalytic performance parameters were established. The Pareto analysis results show that Brunauer–Emmett–Teller (BET) specific surface (A) has little effect on the photocatalytic system, and the most important parameter is the interaction between Energy gap (Eg) and Photoluminescence (PL) intensity (B-C) that has a positive effect on photocatalytic reaction kinetics. The single-factor Eg (B) and PL intensity (C) have negative effects on UV photocatalytic reaction kinetics. This work can help narrow the range of the optimal W R of P25-TiO 2 for emerging organic pollutants.