Lower Carrier Recombination Rate Research Articles

Enhanced Performance of HTM-Free Perovskite Solar Cells with Free-Standing Carbon Electrode via Surface Treatment and Conductive Support

This study explores the optimization of hole transport material (HTM)-free perovskite solar cells featuring laminated free-standing carbon film as a back electrode. Surface treatment of perovskite film using different types of solvent (chlorobenzene, toluene, and ethyl acetate) was carried out to improve the electrical contact at the carbon/methylammonium lead iodide interface. Overall, the surface treatment improved mechanical adhesion between the perovskite and carbon film. The conductivity of the free-standing carbon electrode was further improved by attaching the carbon film to various types of conductive support. Our results show that the selection of both solvents used during surface treatment and the type of conductive substrate has a considerable impact on the resulting performance, wherein all modifications gave rise to substantial improvement over the benchmark unmodified carbon electrode. A power conversion efficiency (PCE) of 7.74% was achieved by the perovskite solar cell with laminated carbon electrode on Al foil combined with the application of chlorobenzene as surface treatment, demonstrating a tremendous increase in performance compared to that of untreated free-standing carbon electrode that produced PCE less than 1%. The main contributor to the improved performance is presumably due to the low carrier recombination rate and improved charge carrier extraction as implied by the electro-impedance spectroscopy and photoluminescence analysis. This work demonstrates a facile approach for resolving the challenges in developing low-cost HTM-free perovskite solar cells with a free-standing carbon film electrode.

Janus SMoZAZ′ (A = Si, Ge; Z, Z′ = N, P, As; Z ≠ Z′) monolayers: potential water-splitting photocatalyst with low carrier recombination rate

Janus SMoZAZ′ monolayers exhibit excellent photocatalytic performance.

Two-dimensional SPdAZ2 (A = Si, Ge; Z = N, P, As) monolayers with an intrinsic electric field for high-performance photocatalysis.

Two-dimensional materials exhibiting exceptional photocatalytic properties and a low carrier recombination rate have garnered significant attention. However, such attributes are relatively scarce among conventional two-dimensional materials. Two-dimensional Janus materials, owing to their intrinsic electric field, hold substantial promise in the realm of photocatalysis. In this study, we conducted a comprehensive investigation of the electronic, optical and photocatalytic properties, as well as the carrier mobility of SPdAZ2 (A = Si, Ge; Z = N, P, As) monolayers employing first-principles calculations. Employing the HSE06 hybrid density functional, we discovered that all six structures exhibit semiconductor characteristics with indirect band gaps under equilibrium conditions. Notably, SPdSiP2, SPdSiAs2, and SPdGeP2 monolayers displayed advantageous band edge positions, facilitating effective photocatalytic water decomposition. Furthermore, we computed the carrier mobility of SPdAZ2 monolayers, revealing significant variations in the electron and hole mobility along the same direction, which enhances the effective separation of electrons and holes. Finally, we explored the impact of biaxial strain and an applied electric field on the electronic properties, photocatalysis, and light absorption of SPdAZ2 monolayers. These compelling features underscore the broad potential applications of SPdAZ2 (A = Si, Ge; Z = N, P, As) monolayers in the realm of photocatalytic water decomposition.

Two-dimensional CsPbI3/CsPbBr3 vertical heterostructure: a potential photovoltaic absorber

First-principles methods have been employed here to calculate structural, electronic and optical properties of CsPbI3 and CsPbBr3, in monolayer and heterostructure (HS) (PbI2-CsBr (HS1), CsI-CsBr (HS2), CsI-PbBr2 (HS3) and PbI2-PbBr2 (HS4)) configurations. Imaginary frequencies are absent in phonon dispersion curves of CsPbI3 and CsPbBr3 monolayers which depicts their dynamical stability. Values of interfacial binding energies signifies stability of our simulated heterostructures. The CsPbI3 monolayer, CsPbBr3 monolayer, HS1, HS2, HS3 and HS4 possess direct bandgap of 2.19 eV, 2.73 eV, 2.41 eV, 2.11 eV, 1.88 eV and 2.07 eV, respectively. In the HS3, interface interactions between its constituent monolayers causes substantial decrease in its resultant bandgap which suggests its solar cell applications. Static dielectric constants of all simulated heterostructures are higher when compared to those of pristine monolayers which demonstrates that these heterostructures possess low charge carrier recombination rate. In optical absorption plots of materials, the plot of HS3 displayed a red shift and depicted absorption of a substantial part of visible spectrum. Later on, via Shockley-Queisser limit we have calculated solar cell parameters of all the reported structures. The calculations showed that HS2, HS3 and HS4 showcased enhanced power conversion efficiency compared to CsPbI3 and CsPbBr3 monolayers when utilized as an absorber layer in solar cells.

Solar driven photocatalytic disinfection by Z-scheme heterojunction of In2O3/g-C3N4: Performance, mechanism and application

To realize an efficient solar disinfection, Z-scheme In2O3/g-C3N4 heterojunctions were prepared and its performances were investigated. The In2O3/g-C3N4 exhibits a wide light response range and a low carrier recombination rate. Due to the transfer of electron (e-) and hole (h+) between In2O3 and g-C3N4, the generations of superoxide (O2•-) and hydroxyl radicals (HO•) were enhanced. O2•−, HO• and h+ played important roles for disinfection. Approximately 106 CFU/mL E. coli were inactivated within 90 min. In addition to cell membrane lysis, DNA was degraded. In2O3/g-C3N4 still revealed high sterilization efficiencies under natural sunlight or for actual wastewater treatment. Although humic acid and inorganic anions (Cl‾ < NO3‾ < SO42‾ < H2PO4‾ < HCO3‾) inhibited the disinfection, detection limit (DL, about 5.8-log removal) can be achieved. Furthermore, DL still could be achieved and the In2O3/g-C3N4 structure remained intact after 5 cycles. This study provides novel guidance for solar-driven water purification.

Constructing S-scheme heterojunctions through electrostatic self-assembly of Co3O4 quantum dots and CuBr for photocatalytic hydrogen evolution

Utilizing solar energy to power semiconductors for water splitting and hydrogen production is an effective method for clean energy generation. This study presents a new S-scheme heterojunction catalyst, constructed via electrostatic self-assembly of CuBr and Co3O4 quantum dots. The band gap-matching positions and energy band structures of CuBr and Co3O4 quantum dots are well-suited for this purpose. The hydrogen precipitation performance of the resulting CQCB2 catalyst is approximately four times higher than that of a single catalyst. Additionally, CQCB2 exhibits good stability, with an 80% hydrogen precipitation efficiency after four consecutive cycles. The study demonstrates that CQCB2 exhibits a high absorbance intensity, efficient charge separation, low electron transport resistance, and low photogenerated carrier recombination rate. This is further validated by XPS and UPS experiments, which support the S-scheme heterojunction charge transfer mechanism. Overall, this paper provides a unique insight into the study of S-scheme heterojunction catalysts.

Two-in-one additive engineering strategy induced high-quality CsPbBr3 film in printable mesoscopic perovskite solar cells

The use of all-inorganic cesium lead tribromide (CsPbBr3) in photovoltaics has gained significant attention due to its outstanding environmental stability and low cost of preparation. Printable perovskite solar cells (PSCs) based on CsPbBr3 have demonstrated a more straightforward fabrication procedure and remarkable stability, indicating great development potential. However, the preparation of the CsPbBr3 film can be challenging, as it requires depositing a high-quality PbBr2 film in a triple-layer porous scaffold and avoiding the incomplete conversion of PbBr2 in the subsequent step. Herein, we propose a two-in-one additive engineering strategy using 4-tert-Butylpyridine (TBP) into the PbBr2 solution and dimethyl sulfoxide (DMSO) to the CsBr precursor. The improved perovskite layer with better infiltration in scaffold, low carrier recombination rate and high absorption ability results in the boosting performance of PSCs. When the TBP is coupled with DMSO to fabricate printable mesoscopic CsPbBr3 PSCs, the device achieves a power conversion efficiency as high as 8.36 %. Furthemore, the modified CsPbBr3 PSC without any encapsulation retains above 97 % of its initial efficiency after 1600 h of storage in ambient air, indicating outstanding stability.

Porphyrin-Based Carbon Dots for Efficient Photocatalytic Reduction of CO&lt;sub&gt;2 &lt;/sub&gt;to Methanol

Photocatalytic CO2 reduction to solar fuel is a potential way to overcome the problem of high carbon dioxide concentrations; however, the process still faces enormous challenges, such as the low light absorption efficiency and high carrier recombination rates. This work synthesized tetraphenylporphyrin-based carbon dots (TPP-CDs) for the photocatalytic CO2 reduction to CH3OH under simulated sunlight to extend the absorption region of the CDs. The conduction band of the TPP-CDs has a sufficiently negative reduction potential to reduce CO2. TPP-CDs containing 1 wt.% TPP achieved an optimum CH3OH production rate of 173.35 μmol·gcat-1·h-1, with a remarkable 2.06-fold increase compared to pristine CDs without TPP. In this study, TPP-CDs were synthesized by changing the CD precursors to improve the utilization of visible light and apply them to the photocatalytic reduction of CO2.

Highly photoactive novel NiS/BiOI nanocomposite photocatalyst towards efficient visible light organic pollutant degradation and carcinogenetic Cr (VI) reduction for environmental remediation

Heterojunction engineering in catalyst structures is a promising approach for solving the main restriction of the narrow photoabsorption range and quick recombination of photogenerated charge carriers in the photocatalysts. Herein, a simple, eco-friendly, non-toxic, and novel Z-scheme heterojunction of nanoflower-like NiS/BiOI was systematically designed using the low-temperature solvothermal and precipitation methods. The physicochemical and photo-electrochemical properties of the as-synthesized nanomaterials were characterized using XRD, FESEM, FT-IR, XPS, BET, UV–vis, PL, and EIS. NiS/BiOI nanomaterials exhibited a wide photoabsorption range (200–1000 nm), a narrow bandgap energy (1.76 eV), a large surface area (35.82 m2 g-1), and a low charge carrier recombination rate because of the synergistic effects of the NiS and BiOI photocatalysts, which could be the basis for superior photocatalytic efficiency. Particularly, the optimal 40% NiS/BiOI nanocomposite exhibited better stability and efficiency than the pure NiS and BiOI. The maximum degradation efficiency of rhodamine B (RhB) was 99.8% after 200 min, tetracycline (TC) was 96.3% after 140 min, and the photoreduction of Cr(VI) was 92.8% after 180 min rather than the pure NiS and BiOI under visible light irradiation. The constant rate (k) of RhB was approximately 10 and 4, TC was 12 and 4, and Cr(VI) was 10 and 8 times that of pristine NiS and BiOI, respectively. Radical trapping experiments and Tauc plot analysis proposed the design of the plausible Z-scheme reaction mechanism between NiS and BiOI, which has a crucial role in the rate of transportation and separation of electron/hole pairs. This investigation provides a venue for the design of a photoactive NiS-based nanocomposite for environmental remediation.

Investigation of thickness dependent efficiency of CsPbX3 (X = I, Br) absorber layer for perovskite solar cells

The drawbacks of solar cells consisting of hybrid organic-inorganic lead halide perovskites led to the development of solar cells containing completely inorganic perovskites. Therefore, here we have carried out detailed density functional theory (DFT) based investigation of cubic phase CsPbX3 (X = I, Br). Absence of imaginary frequencies in phonon dispersion curves and negative cohesive energies of the perovskites depicts stability of our crystal structures. From electronic properties of CsPbI3 and CsPbBr3 we have deduced that the major contributions in their valence band region is due to I-5p and Br-4p orbitals, respectively. The static dielectric constant of CsPbI3 is greater than CsPbBr3 which shows that it consists of low carrier recombination rate. Red shift has also been observed in absorption coefficient plot while going from Br → I in CsPbX3. The thickness of absorber layer present in perovskite solar cells (PSCs) directly influences its efficiency and stability. Therefore, here we have used a detailed framework i.e., spectroscopic limited maximum efficiency (SLME) to predict solar cell parameters of perovskites absorber layer as a function of their thicknesses. Using SLME approach which is thickness dependent it has been predicted that at thicknesses above 2.56 μm and 1.39 μm of absorber layers CsPbI3 and CsPbBr3, respectively, their efficiencies obtained using SLME approach are higher compared to that obtained using Shockley-Queisser (SQ) limit. The efficiencies of CsPbI3 and CsPbBr3 absorber layers calculated using SLME approach at absorber thickness of 20 μm are obtained around 30.41% and 24.53%, respectively.

Crosslinking and densification by plasma-enhanced molecular layer deposition for hermetic seal of flexible perovskite solar cells

Flexible perovskite solar cells are new energy devices with a promising future due to their numerous advantages, such as high defect tolerance, strong solar absorption and low non-radiative carrier recombination rates. However, their operational stability is still an ongoing challenge during upgrading, and their inferior moisture corrosion resistance is still a major issue for better performances. Thin-film encapsulation could effectively enhance the operational stability of perovskite solar cells but obtaining encapsulation films with excellent barrier performance always come at the expense of poor flexibility. Therefore, the development of novel encapsulation materials with both barrier performance and flexibility is urgent for the compatibility of flexible applications. In this work, "Plasma-Enhanced Molecular Layer Deposition" was used for the first time to prepare a highly cross-linked, densified flexible encapsulation material AlOC at 40 ℃ to break through the traditional technology. The resulting encapsulation material can be applied to flexible perovskite solar cells as a barrier film without any damage. The as-obtained encapsulation film exhibited a water vapor transmittance rate of 1.44 × 10−5 g m−2 day−1 and preserved 95 % of its initial barrier performance after 10,000 bends with a 3 mm bend radius. Such performance was the best among the reported thin-film encapsulation layers of flexible perovskite solar cells.

Cu-Doped ZnIn2S4/NixP Composites with Enhanced Carrier Dynamics and Photocatalytic Hydrogen Production Performance

Photocatalytic technology still faces enormous challenges to design and synthesize highly efficient photocatalytic materials with a high electron/hole separation efficiency, rapid charge migration, low carrier recombination rate, and strong visible light-harvesting capability. Herein, Cu-doped ZnIn2S4/NixP (marked CuyZIS/NP) composites were successfully synthesized by a simple two-step method. The synergistic effect of Cu2+ doping and the NixP cocatalyst on hydrogen evolution performance was investigated in detail. The results showed that superior photoactivity over CuyZIS/NP composites was achieved. The optimal Cu0.5ZIS/NP-1/2 sample had a hydrogen evolution rate of 4746.3 μmol·g–1·h–1 under visible light irradiation, which was approximately 15.98 times higher than that of pure ZnIn2S4 (297 μmol·g–1·h–1). This work may offer a valuable insight into understanding the synergistic effect of doping and cocatalysis and provide a guideline for designing and developing highly efficient visible light-driven photocatalysts toward a water splitting system.

Large birefringence in the quasi-one-dimensional material Sb2Se3: A DFT investigation of electronic and optical anisotropy

Investigation of the optical and electronic properties of the quasi-one-dimensional semiconductor Sb2Se3 is performed with density functional theory, which takes into consideration the spin–orbit coupling and the on-site Coulomb self-interaction. Sb2Se3 has an orthorhombic crystal structure and belongs to the Pnma space group. The pronounced dispersion along the R−U, Z−Γ, Γ−Y, and S−X high-symmetry directions and low dispersion along the U−Z and Y−S directions confirm the layered structure, with strong bonding interactions along the [001] direction, as well as along the [010] direction, along which the SbSe6 and SbSe7 chains are aligned, and weak van der Waals interactions along the [100] direction. The material is a semiconductor with an indirect bandgap of 1.2 eV. Sb2Se3 exhibits appreciable carrier mobility and low carrier recombination rates in the plane of the layers, indicating its applicability in solar and photovoltaic devices. Simulated X-ray photoelectron spectra show that the photoelectron emission occurs from the Se p, Sb s, and Se s atomic orbitals, while for high-energy X-rays, photoelectron emission is mainly from Sb s orbital. Sb2Se3 possesses appreciable anisotropy in its refractive index, absorption coefficient, reflectivity, extinction coefficient, and optical conductivity. Sb2Se3 is a negative biaxial crystal, in which the principal optical axis X→a, Y→b, and Z→c. It possesses uniform birefringence in the IR region until the optical cutoff edge at 1030 nm. The material shows strong unidirectional linear dichroism in the wavelength range from 300 nm to 620 nm, with linear dichroism conversion at 275 nm. The energy loss is isotropic for slow electrons below 4.0 eV, but for highly energetic electrons it varies along different crystal directions. Sb2Se3 is a promising material for optoelectronic and polarimetric applications because of its desirable bandgap of 1.2 eV, linear dichroism conversion, and large optical anisotropy, refractive index, dielectric constant, and absorption coefficient.

Coral-like Sb2Se3/SnS2 photocathode co-optimized by bilayer Sb2Se3 structure and hole-storage layer for photoelectrochemical water splitting

Achieving high light absorption efficiency and low photogenerated carrier recombination rates is critical in the production of H 2 by photoelectrochemical water splitting. Antimony selenide (Sb 2 Se 3 ) has recently received much attention due to its favorable optoelectronic properties, low cost and unique nanorod structure. Herein, we constructed coral-like Sb 2 Se 3 /SnS 2 heterojunction by introducing SnS 2 with a nanosheet structure, which contributes to enhanced light absorption and provides more reaction sites. On this basis, synergistic optimization is carried out by the bilayer Sb 2 Se 3 structure and ferrihydrite (Fh) to effectively inhibit charge recombination at the interface and facilitate electron transport. Compared to monolayer Sb 2 Se 3 (1.54%), the IPCE value of bilayer Sb 2 Se 3 /SnS 2 /Fh can reach 20.56% (735 nm). The prepared bilayer Sb 2 Se 3 /SnS 2 /Fh has a maximum photocurrent density of approximately − 1.0 mA cm −2 at 0 V RHE , continuous testing for 1 h compared to monolayer Sb 2 Se 3 still maintains more than 4 times improvement. This work provides a basis for the development of high efficiency and low cost Sb 2 Se 3 -based optoelectronic devices. • The bilayer Sb 2 Se 3 structure was constructed by sequential deposition. • A combination between 1D Sb 2 Se 3 nanorods and 2D SnS 2 nanosheets has been achieved. • Surface modification using ferrihydrite as an interface engineering material. • Optimized photoelectrode current density is 50 times higher than original sample. • The PEC mechanism of bilayer Sb 2 Se 3 /SnS 2 /Fh photoelectrode was proposed.

Dual-Band, Efficient Self-Powered Organic Photodetectors with Isotype Subphthalocyanine-Based Heterojunctions toward Secure Optical Communications

High-performance heterojunction organic photodetectors (OPDs) are of great significance in optical detecting technology due to their tailorable optoelectronic properties. Herein, we designed and synthesized three n-type subphthalocyanine (SubPc) derivatives PhO-BSubPcF12, CHO-PhO-BSubPcF12, and NO2-PhO-BSubPcF12 via axial nonhalogen substitution on fluorinated SubPc. These SubPc derivatives exhibit improved intramolecular charge transfer, high electron mobilities, optimized energy levels, and good thermal stability. The novel isotype p-n SubPc heterojunctions are evaluated as photosensitive layers in OPDs, which show a UV-visible dual-band response and self-powered effect. The optimal OPD with Br-BSubPc/NO2-PhO-BSubPcF12 presents stable and superior performances with a high responsivity (R) of 0.14 A W-1, a peak external quantum efficiency (EQE) of 30.6%, and an extremely low dark current of 0.92 nA cm-2 under a 570-595 nm illumination without a bias voltage. It has outperformed most of the reported SubPc-based OPDs. The better interfacial contact of p-n SubPc derivatives leads to a large depletion region with decreased trap densities as well as a low carrier recombination rate, which is conducive to the photoinduced carriers' separation and well-balanced transport, resulting in high device performances. Moreover, a secure communication strategy is successfully demonstrated by dual-band optimal OPD. This work is expected to provide some guidance for molecular engineering and device performance toward multifunctional electronics.

Porous BiVO4/Boron-Doped Diamond Heterojunction Photoanode with Enhanced Photoelectrochemical Activity.

Constructing heterojunction is an attractive strategy for promoting photoelectrochemical (PEC) performance in water splitting and organic pollutant degradation. Herein, a novel porous BiVO4/Boron-doped Diamond (BiVO4/BDD) heterojunction photoanode containing masses of ultra-micro electrodes was successfully fabricated with an n-type BiVO4 film coated on a p-type BDD substrate by magnetron sputtering (MS). The surface structures of BiVO4 could be adjusted by changing the duration of deposition (Td). The morphologies, phase structures, electronic structures, and chemical compositions of the photoanodes were systematically characterized and analyzed. The best PEC activity with the highest current density of 1.8 mA/cm2 at 1.23 VRHE was achieved when Td was 30 min, and the sample showed the highest degradation efficiency towards tetracycline hydrochloride degradation (TCH) as well. The enhanced PEC performance was ascribed to the excellent charge transport efficiency as well as a lower carrier recombination rate, which benefited from the formation of BiVO4/BDD ultra-micro p-n heterojunction photoelectrodes and the porous structures of BiVO4. These novel photoanodes were expected to be employed in the practical PEC applications of energy regeneration and environmental management in the future.

Graphdiyne (g-CnH2n-2) based Co3S4 anchoring and edge-covalently modification coupled with carbon-defects g-C3N4 for photocatalytic hydrogen production

Graphdiyne (GDY), as a novel two-dimension carbon allotrope material composed of sp- and sp2-hybrid carbon network, has been widely explored since it was synthesized for the first time by Li’s group in 2010. In this research, we developed a synthesis scheme of Co3S4-anchored graphdiyne/carbon defects g-C3N4 (DCN) nano-hybrids for efficient photocatalytic hydrogen evolution. This system has a fantastic 0D-2D/2D structure and the porous interconnected framework favors multivariate collaborative catalysis, greatly promoting the mass transfer performance between them, and enhancing the light absorption and the density of active sites. Most of all, as a charge transfer station, the edge-covalently modified GDY provides shortcuts for the dual-induction of electrons and holes. Charge kinetic analysis indicated that the electron transfer rate of the system reached 9.27 × 109 s−1, and the ultra-fast interfacial transfer considerably promoted the charge separation. In addition, photoelectrochemical technology verified that the multiplex nanoreactor has lower carrier recombination rate and smaller hydrogen evolution overpotential. Under 5 W LED light (λ > 420 nm), the dye-sensitized optimized hydrogen generation rate is 2075.67 μmol g−1 h−1, which is 77.2 times that of bare DCN. This work is expected to develop a new design concept for the construction of multiple and efficient synergistic nanocomposites, opening up new opportunities and possibilities for photocatalysis applications.

Enhanced Carrier Separation in Visible-Light-Responsive Polyoxometalate-Based Metal-Organic Frameworks for Highly Efficient Oxidative Coupling of Amines.

Photocatalytic technology is widely studied, while it comes with drawbacks such as low sunlight utilization efficiency and high carrier recombination rates. Herein, for the first time, we present two crystalline polyoxometalate (POM)-based metal-organic frameworks (POMOFs), {[Cd(DMF)2Ru(bpy)2(dcbpy)]2(POMs)(DMF)2} xDMF (PMo-1, POMs = [PMoVI11MoVO40]4-, x = 5; SiW-2, POMs = [SiW12O40]4-, x = 4) through assembling the photosensitizer [Ru(bpy)2(H2dcbpy)]Cl2 and POMs into a single framework. The assembly not only enhances light absorption in the visible light regime but also improves carrier separation efficiency; atop of that, both POMOFs demonstrate activities in the photocatalytic oxidative coupling of amines. Particularly, PMo-1 enables the quantitative completion of oxidative coupling of benzylamine reaction within 30 min (yield = 99.6%) with a high turnover frequency (TOF = 6631.6 h-1). To our knowledge, the PMo-1 catalyst outperforms any other photocatalysts previously reported in similar use cases where TOF values were usually obtained <2000 h-1.

Effect of carbon nitride synthesized by different modification strategies on the performance of carbon nitride/PVDF photocatalytic composite membranes

Carbon nitride (CN)/polyvinylidene fluoride (PVDF) photocatalytic composite membrane (PCM) is considered as a promising candidate to improve the anti-fouling characteristic of conventional PVDF membrane and overcome the difficulty encountered during recovery of powder catalyst simultaneously. However, the effects of differently-modified CN on PCM and its mechanism are still unclear. In this study, bulk-CN (BCN), carbon defects CN (CCN), nitrogen defect CN (DCN), mesoporous CN (MCN), and nitrogen-rich CN (NCN) were incorporated into PVDF by phase inversion method. The influence of changes in the physical and chemical properties of CN, including hydrophilic groups, photocatalytic activity, and particle size, on the permeability, anti-fouling characteristic, and photocatalytic self-cleaning activity of CN/PVDF was systematically analyzed. The mechanism of excellent performance of PCM was revealed by experimental test and theoretical calculation. The flux of PCM was significantly improved by increasing the hydrophilic group on modified CN. However, the differences in particle size and interaction between different types of modified CN and PVDF chains endowed the CN/PVDF with different porosity. DCN/PVDF showed high porosity and hydrophilicity, leading to high water flux and rejection rate of 293.6 L (m2 h)−1 and 90.1%, respectively. Compared to pure PVDF, the flux recovery rate of DCN30/PVDF increased by 27.6%, and the irreversible fouling decreased from 36.9% to 9.2%. The modified CN/PVDF showed excellent photocatalytic activity for the removal of cefotaxime (CFX) and E. coli. Owing to the narrow band gap of DCN, large specific surface area, and low photogenerated carrier recombination rate, the CFX removal rate reached 99% in 2 h, and E. coli inactivation achieved 3.7 log within 4 h via DCN30/PVDF.

Manipulating the electronic and photocatalytic properties of anatase TiO2 by metalloid doping

Improving the photocatalytic efficiency of photocatalysts is one of the most challenging and meaningful research topics. In this work, using first principles study, the crystal structure, formation energy, electronic structures and photocatalytic properties of metalloid doped TiO2 were investigated. The results show that Si and Te doped TiO2 have excellent photocatalytic activity in the entire visible light spectrum. This is because they have high visible light absorption efficiency, low photogenerated carrier recombination rate and more catalytic active sites. This work provides essential guidance for developing TiO2-based visible light photocatalysis.