Charge Transfer Distance Research Articles

Photovoltaic and spectroscopic properties of bacteriochlorin-based photosensitizer: molecular approach

The biophotovoltaic features of the porphyrin- and bacteriochlorin-based solar cells in different media were investigated through quantum chemistry calculations. The results show that a decrease in the chemical potential and electrophilicity facilitates the charge transfer process. Also, the bacteriochlorins have a lower energy barrier of electron injection than that of porphyrin, because of a longer charge transfer distance and less electron–hole overlap. Moreover, nonpolar solvents accelerate the free charge production, due to the favorable changes in the exciton radius and exciton binding. Improved spectroscopic properties are observed for the dyes in the solvent medium, which may be related to an increment in the probability of the electronic transition and reduced band gaps. Based on the simulated absorption spectra, bacteriochlorins are the preferred light-harvesting materials than porphyrin in the visible region. Moreover, the development of the push–pull model in the bacteriochlorin structure increases their energy conversion ability, due to advanced quantum chemistry reactivity properties. According to the final efficiency, bacteriochlorins are the preferred candidates in comparison with porphyrin to be applied in the dye-sensitized solar cells, in agreement with the experimental results.

Photovoltaic Effect in Phthalocyanine-Based Organic Solar Cells: 1. Thermal Ionization of Molecular Excitons

Based on the previously obtained data [1, 2], according to which the photoelectric quantum yield (Y) in crystals of the β-form of metal-free phthalocyanine and copper phthalocyanine is the same for electrons and holes and has an Arrhenius temperature dependence with an activation energy EY equal to the difference between the band gap and the molecular exciton (ME) energy, a three-dimensional stochastic model of thermal ionization of MEs is proposed, which is considered as a sequence of reversible transitions from the ME to the lowest charge-transfer (CT) state and then to a CT state with an increasing charge-transfer distance. A relationship has been found between EY and the radial density of CT states at which the probability of charge separation is greater than that of the decay of these states.

Water-stable Mn-based MOF nanosheet as robust visible-light-responsive photocatalyst in aqueous solution

Development of visible-light-responsive metal-organic frameworks (MOFs) for promising solar energy conversion has inspired continuous interest, but it still suffers from poor stability especially in aqueous solution and/or under photoirradiation due to their relatively labile coordination bonds. Herein, a new synthesized layered Mn-based MOF (Mn-TBAPy-BK) and its exfoliated two-demensional nanosheets (Mn-TBAPy-NS) are revealed to be highly stable no matter in aqueous solution with wide pH region or under visible light irradiation. As expected, the exfoliated Mn-TBAPy-NS exhibits enhanced surface area, shortened charge transfer distance, and superior charge separation with respect to the bulk one. Moreover, the as-obtained nanosheets can be employed as effective building block for nanocomposite and heterostructure assembly to further promote charge separation as well as solar hydrogen production from aqueous solution under visible light. The finding of water stable MOF nanosheet under visible light demonstrates its promising future for solar energy conversion.

Fabrication of CdS Frame-in-Cage Particles for Efficient Photocatalytic Hydrogen Generation under Visible-Light Irradiation.

The design of advanced structures for semiconductor photocatalysts is an effective approach to enhance their performance toward solar-to-chemical energy conversion. Hollow and frame-like structures show advantageous features for photocatalytic reactions with enlarged surface area, shortened charge-transfer distance, promoted light-absorption ability, and enhanced mass-transfer capability. Here, a facile two-step sulfidation strategy is developed to fabricate unique CdS frame-in-cage particles for photocatalytic hydrogen generation. Cd-based Prussian blue analog (Cd-PBA) cubes are first converted to Cd-PBA cube-in-CdS cage particles, which are further transformed to CdS frame-in-cage particles. Benefiting from the novel frame-in-cage structure, the obtained CdS photocatalyst exhibits high activity under visible-light irradiation with the hydrogen generation rate of 13.6mmol h-1 g-1 , which is much enhanced compared with those of the CdS cubes and cages.

Hydrogen peroxide sensing in body fluids and tumor cells via in situ produced redox couples on two-dimensional holey CuCo2O4 nanosheets.

Anovel nanomaterial of two-dimensional holey CuCo2O4 (2D HCCO) nanosheets was synthesized via a general template-directed method and employed for the first timeto construct an effective electrochemical platform for H2O2 sensing with the combination of cerium oxide (CeO2). During the electrocatalytic reduction of H2O2, the synergetic catalysis of CeO2/HCCO/MWCNTs/GCE owing to the naturally holey frameworks and the mediator of CeO2 results in the ultra-sensitive detection of H2O2. The current was greatly enhanced owing to the unique holey structure that can minimize the charge transfer distance and provide more active sites to boost the signals, and the dual oxidation state of Ce3+/Ce4+ on the surface of 2D HCCO nanosheets can promote the in situ production of Cu2+/Cu+ and Cu+/Cu and further amplify the detection signal. The CeO2/HCCO/MWCNTs/GCE showed a wide linear range from 1μM to 7.31mM using chronoamperometry at the potential of - 0.25V and a relatively low detection limit of 0.16μM in physiological environment, which was also utilized for tracking the trace H2O2 released from Hela cells. This study shows great promise for the emerging application of holey HCCO-based biosensors in bioanalysis and early cancer diagnosis. Graphical abstract.

First-principles study of CO and NO adsorption on pristine and transition metal doped blue phosphorene

First-principles calculations within the density functional theory (DFT-D2 method) is carried out to systematically investigate the structural, energetic, electronic and magnetic properties of toxic CO and NO gas molecules on pristine and transition metal (TM) atom (Fe, Co, Ni, Pd, Ag and Pt) doped blue phosphorene. Our calculations show that the CO and NO molecules are physisorbed on pristine blue phosphorene due to small adsorption energies, charge transfer, and large adsorption distances of the adsorbed systems. TM doping can significantly enhance the interaction between the gas molecules and the blue phosphorene, leading to the CO and NO molecules absorbed on TM doped blue phosphorene belong to chemisorption with relatively large adsorption energies and charge transfer, except for CO adsorbed on Ag doped blue phosphorene. Meanwhile, the enhancing interaction between the gas molecules and TM doped blue phosphorene can dramatically induce magnetism and electrical conductivity changes. These results indicate that TM doped blue phosphorene is a potential candidate to develop novel two-dimensional phosphorene-based gas sensors.

Exploring anchoring performance of InP3 monolayer for lithium-sulfur batteries: A first-principles study

Lithium-sulfur (Li-S) batteries have received much exploration these years, and developing suitable anchoring materials is a great challenge to improve the performance of the batteries. In this study, first-principles with density functional theory study was adopted to investigate the anchoring behavior of lithium polysulfides (LiPSs) on InP3 monolayer. The structures of different LiPSs adsorbed on InP3 monolayer were obtained by calculating the adsorption energy, charge transfer and adsorption distance. The electron distribution and the electronic properties were investigated and the stability of LiPSs on InP3 monolayer was studied. The results indicate that InP3 monolayer shows strong chemical interactions with LiPSs because of the considerable adsorption energies (from −1.08 eV to −4.43 eV in vacuum and −0.94 eV to −3.21 eV in DME/DOL solvent). The adsorption of LiPSs on InP3 monolayer can also result in electron redistribution and reduction of the energy gap near Fermi-level in density of states (DOS). Moreover, InP3 monolayer can also maintain a balance between anchoring and intactness of LiPSs. Our study demonstrates that InP3 monolayer can be an excellent anchoring material for Li-S batteries and can provide theoretical basis of exploring novel 2D materials in field of energy storage.

Electroactive Molecularly Imprinted Polymer for Selective Detection of 4-Nitrophenol

We propose to develop a reusable electro-chemical sensor for selective detection of 4-nitrophenol (4-NP), based on molecularly imprinted polymer (MIP) technology. MIP technology is the design of an artificial receptor with high selectivity for a specific analyte. Our approach combines N-isopropylacrylamide (NIPAM) backbone polymer with different functional monomers to improve the selectivity and sensitivity of 4-nitrophenol (4-NP) detection.The key points of our sensor polymer are:1) reduced amount of covalent crosslinker methylene bis-acrylamide (MBA) to increase rebinding kinetics and affinity and 2) modified polymer backbone with an electroactive block deposited on a gold surface. To get rapid high affinity template rebinding, we used a reduced amount of covalent crosslinker and used noncovalent crosslinking based on acid-base and hydrophobic interactions. To form acid-base crosslinking, we used 4-vinylpyridine (4-VP) as the basic monomer and methacrylic acid (MAA) as acidic monomer.In MIPs synthesis part, our strategy takes the advantage of reversible addition fragmentation-chain transfer (RAFT) polymerization to control the polymer chain length and modify the terminus as poly-ferrocene methyl methacrylate (FMMA), an electroactive block. The RAFT agent contains R group and Z group which are at different ends of polymer. The Z side is reduced to a thiol and deposited on gold. The PolyFMMA block is on the R side. RAFT agent, FMMA monomers and initiator were added to a batch system to synthesis the first electroactive block. Then, all chemicals including backbone monomers, functional monomers, crosslinkers and templates (4-NP) were added to form the major polymer block. After synthesis, templated-MIPs were dialyzed to remove the template for further target selective detection.One of the major challenges of our sensor is polymer tangling which affect measurement stability. To reduce polymer tangling effects, we dissolved the template-removed MIPs into tetrahydrofuran (THF) and controlled the gold electrode surface coverage. We deposited MIPs on an additional flat gold chip and used atomic force microscope (AFM) to characterize the surface coverage distribution.The modified gold electrode can be used in electrical impedance spectroscopy (EIS) or cyclic voltammetry (CV) to measure charge transfer distance before and after template rebinding to detect unknown concentration target analytes.

Synthesis of Ni2+ cation modified TS-1 molecular sieve nanosheets as effective photocatalysts for alcohol oxidation and pollutant degradation

Improvement of the charge separation of titanosilicate molecular sieves is critical to their use as photocatalysts for oxidative organic transformations. In this work, MFI TS-1 molecular sieve nanosheets (TS-1 NS) were synthesized by a low-temperature hydrothermal method using a tailored diquaternary ammonium surfactant as the structure-directing agent. Introducing Ni2+ cations at the ion-exchange sites of the TS-1 NS framework significantly enhanced its photoactivity in aerobic alcohol oxidation. The optimized Ni cation-functionalized TS-1 NS (Ni/TS-1 NS) provide impressive photoactivity, with a benzyl alcohol (BA) conversion of 78.9% and benzyl aldehyde (BAD) selectivity of 98.8% using O2 as the only oxidant under full light irradiation; this BAD yield is approximately six times greater than that obtained for bulk TS-1, and is maintained for five runs. The excellent photoactivity of Ni/TS-1 NS is attributed to the significantly enlarged surface area of the two-dimensional morphology TS-1 NS, extra mesopores, and greatly improved charge separation. Compared with bulk TS-1, Ni/TS-1 NS has a much shorter charge transfer distance. The as-introduced Ni species could capture the photoelectrons to further improve the charge separation. This work opens the way to a class of highly selective, robust, and low-cost titanosilicate molecular sieve-based photocatalysts with industrial potential for selective oxidative transformations and pollutant degradation.

WITHDRAWN: Exploring Anchoring Performance of InP3 Monolayer for Lithium-sulfur batteries: A First-principles study

Abstract Lithium-sulfur (Li-S) batteries have received much exploration these years, and developing suitable anchoring materials is a great challenge to improve the performance of the batteries. In this study, first-principles with density functional theory study was adopted to investigate the anchoring behavior of lithium polysulfides (LiPSs) on InP3 monolayer. The structures of different LiPSs adsorbed on InP3 monolayer were obtained by calculating the adsorption energy, charge transfer and adsorption distance. The electron distribution and the electronic properties were investigated and the stability of LiPSs on InP3 monolayer was studied. The results indicate that InP3 monolayer shows strong chemical interactions with LiPSs because of the considerable adsorption energies (from −1.08 eV to −4.43 eV in vacuum and −0.94 eV to −3.21 eV in DME/DOL solvent). The adsorption of LiPSs on InP3 monolayer can also result in electron redistribution and reduction of the energy gap near Fermi-level in density of states (DOS). Moreover, InP3 monolayer can also maintain a balance between anchoring and intactness of LiPSs. Our study demonstrates that InP3 monolayer can be an excellent anchoring material for Li-S batteries and can provide theoretical basis of exploring novel 2D materials in field of energy storage.

Stark Spectroscopic Evidence that a Spin Change Accompanies Light Absorption in Transition Metal Polypyridyl Complexes.

The "Franck-Condon" (FC) excited state is the first state created when a molecule absorbs a visible photon. Here we report Stark and visible absorption spectroscopies that interrogate the FC state of rigorously diamagnetic [M(bpy)3]2+ complexes, where bpy is 2,2'-bipyridine and M = Fe, Ru, and Os. Direct singlet-to-triplet metal-to-ligand charge transfer (MLCT) transitions are evident in the 550-750 nm region of the absorbance spectrum of [Os(bpy)3]2+, yet are poorly resolved or absent for [Ru(bpy)3]2+ and [Fe(bpy)3]2+. In the presence of a strong 0.4-0.8 MV/cm electric field, well-resolved transitions are observed for all the complexes in this same spectral region. In particular, an electroabsorption feature at 633 nm (15 800 cm-1) provides compelling evidence for the direct population of a high spin [Fe(bpy)3]2+* MLCT excited state. Group theoretical considerations and Liptay analysis of the Stark spectra revealed dramatic light-induced dipole moment changes in the range [Formula: see text] = 3-9 D with the triplet transitions consistently showing shorter charge transfer distances. The finding that the spin of the initially populated FC excited state differs from that of the ground state, even with a relatively light first row transition metal, is relevant to emerging applications in energy up-conversion, dye sensitization, spintronics, photoredox catalysis, and organic light emitting diodes (OLEDs).

Surface reformation of 2D MXene by in situ LaF3-decorated and enhancement of energy storage in lithium-ion batteries

The two-dimensional transition metal carbides or nitrides Ti3C2Tx (MXene), has emerged as attractive electrode materials for lithium-ion batteries due to their metallic electrical conductivity and low ion diffusion barrier. However, the stabilities, electronic structures and other physicochemical properties of MXene are affected intensively by their surface species and structure. Here, a new architecture approach is demonstrated for reforming MXene through in situ-decorated LaF3, for boosting the performance of Li batteries in terms of capacity and rate ability. Ti3C2Tx@LaF3 can deliver an initial specific discharge capacity of 340 mAh/g under a current density of 50 mA/g and a reversible discharge capacity of 89.2 mAh/g at a current density of 1000 mA/g, which is significantly higher than that of pure Ti3C2Tx. Ti3C2Tx@LaF3 heterostructures enhance Li‐ion storage performance by shortens the charge transfer distance and improves the charge transfer rate during electrochemical reaction.

Aromaticity-Photovoltaic Property Relationship of Triphenylamine-Based D-π-A Dyes: Leads from DFT Calculations.

D-π-A-based dyes find a wide range of applications in molecular electronics and photovoltaics in general and dye-sensitized solar cells (DSSC) in particular. We speculated whether there exists a relationship between the degree of aromaticity of the π-spacers used in the D-π-A type dyes and their structural, electronic, energetic, photophysical, and intramolecular charge transfer properties. Triphenylamine (TPA) and cyanoacrylic acid (CAA) have been chosen as the donor and acceptor, respectively. In order to carry out the investigation systematically the π-spacers have been logically chosen based on their experimental resonance energies, which follows the order, furan < pyrrole < thiophene < pyridine < benzene. All the properties have been discussed based on the degree of aromaticity of the π-spacers. Geometric properties such as dihedral angles and bond lengths have been discussed extensively. Energy levels of the frontier molecular orbitals, electrochemical properties, namely, ground and excited state oxidation potentials (GSOP/ESOP), and change in Gibbs free energy for electron injection and regeneration (ΔGinj/ΔGreg) have also been evaluated. Photophysical properties like wavelength of maximum absorption (λmax), oscillator strength (f), light harvesting efficiency (LHE), and intramolecular charge transfer properties, viz., charge transfer distance (DCT), fraction of charge transferred (qCT), and change in dipole moment (μCT) have been assessed. The adsorption characteristics of dye with (TiO2)9 nanocluster have been studied along with their optical properties. Results reveal that the nature of the relationship between the aforementioned properties and the extent of aromaticity of the π-spacers is inherently multifaceted. It thus turns out that it is highly difficult to quantify the relationship. These properties of D-π1-π2-A molecules can be regarded to be arising from two groups, namely, π-spacers with lower and higher resonance energies. This results in a natural trade-off in selection of competing properties. The qualitative aromaticity photovoltaic property relationship thus obtained may serve as a guide to tailor-design various properties of D-π-A type dyes for application in the intramolecular charge transfer devices.

2D tremella-like Co6Al2CO3(OH)16•4H2O in-situ growing on 1D rod-shape ZnFe2O4 to accelerate the surface reaction kinetics for photoelectrochemical water splitting

ZnFe2O4 films applied for photoelectrochemical (PEC) water splitting is still confronted with some challenges like long distance of charge transfer and slow surface reaction kinetics. Herein, ZnFe2O4 films are initially modified by controlling morphology via regulating iron source during the hydrothermal process. A series of measurements demonstrate that one-dimensional (1D) rod-like ZnFe2O4 films possess a better PEC performance (0.11 mA cm−2 at 1.23 V vs. RHE) than that of petal-like ZnFe2O4 films (0.07 mA cm−2 at 1.23 V vs. RHE). Furthermore, the slow surface reaction kinetics of ZnFe2O4 nanorods (NRs) is accelerated by in-situ growing two-dimensional (2D) tremella-like layered double hydroxide Co6Al2CO3(OH)16•4H2O (denoted as CoAl-LDH) through a fugacious hydrothermal method. The photocurrent density of ZnFe2O4/CoAl-LDH is 0.60 mA cm−2 at 1.23 V vs. RHE, which is 5.45 times than that of ZnFe2O4 NRs. Notably, the onset potential of ZnFe2O4/CoAl-LDH is left shifted about 0.19 V–0.77 V vs. RHE compared with ZnFe2O4 NRs (0.96 V vs. RHE). This is ascribed to Co species providing active sites to capture holes for water oxidation reaction and Al species offering the support for layer skeleton. This is a first exemplification of optimizing ZnFe2O4 films for PEC water splitting through tuning morphology and depositing layered double hydroxides, it is meaningful to perceive and conceive efficient PEC devices in the future.

Optimizing the optical and biological properties of 6-(1H-benzimidazole)-2-naphthalenol as a fluorescent probe for the detection of thiophenols: a theoretical study.

The study presents the influence of structure modulation by introduction of selected donor and acceptor substituents on the properties of 6-(1H-benzimidazole)-2(2,4-dinitrobenzenesulfonate)naphthalene used in thiophenol identification. The presence of –OH and –OR groups enhances the non-linear optics (NLO) response of the marker. The –NO2 substituent maximizes the non-linear response and increases the amount of transferred charge and the charge-transfer distance. The introduction of the –OH, –NO2 and –CN groups into the marker structure significantly improves the solubility and optical availability. The –NO2 group however contributes to mutagenicity and carcinogenicity. The –OH and –OR groups can be successfully used in bioimaging to detect specific molecules containing the –SH group in their structure. At the same time, the –OR group minimizes the energy barrier necessary to break the bond between the chromophore and the linker. The paper also includes a comparison of optical and biological properties of structures before and after identification of thiophenols.

Influence of Pd Clusters Doping on Gas Sensing Properties of TiO₂(101) Nanotubes to SF₆ Decomposition Products

Detection and analysis of sulfur hexafluoride (SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> ) decomposition components is one of the most used methods to realize online monitoring of gas insulated switchgear (GIS) faults. In this paper, Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -doped anatase TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (101) surface was constructed, and studied about its geometric and electronic properties to characteristic SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> decomposition products: SOF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> based on DFT calculations. Comparing with intrinsic TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (101), the conductivity of Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (101) surface decreases dramatically. Studies on adsorption energy, charge transfer, and adsorption distance show that Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (101) shows strong chemisorption to SOF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> molecules. Based on density of states and molecular orbital theory analysis, it is found that the adsorption of SOF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> can dramatically change the conductivity in different degrees. As a result, the Pd <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> -TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (101) surface exhibits high gas sensitivity and selectivity to SOF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and SO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> molecules. Our calculations would be meaningful for the development of new sensing materials for SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> decomposition components detection.

An LSPR-based "push-pull" synergetic effect for the enhanced photocatalytic performance of a gold nanorod@cuprous oxide-gold nanoparticle ternary composite.

As promising photocatalysts, nano-sized Cu2O particles suffer from severe charge recombination and insufficient light absorption, resulting in their unsatisfactory photocatalytic performance. Herein, we have designed a core-shell structured Au nanorod@octahedron Cu2O with preferentially edge-loaded Au nanoparticles (Au(R)@Cu2O-Au(P)) for an efficient photocatalytic degradation reaction. A "push-pull" synergetic effect of Au(R) and Au(P) was found to improve the transfer and separation of charge carriers from the bulk to the surface of Cu2O. Furthermore, the light beyond Cu2O particles' absorption range can penetrate the shell (Cu2O) and for being utilized by the Au(R) core via its localized surface plasmon resonance effect (LSPR) to inject hot electrons into the conduction band of Cu2O for photocatalytic reactions. Moreover, the investigation of the size effect of Au(R)@Cu2O-Au(P) reveals that both the short charge transfer distance and the more efficient charge transfer have contributed to its enhanced photocatalytic activity.

Facile fabrication of BiVO4/g-C3N4 photocatalysts and its photocatalytic activity under visible light irradiation

A series of different percentages of BiVO4/g-C3N4 photocatalysts were synthesized by a simple method. These composite materials were characterized by several characterization techniques. BiVO4/g-C3N4 photocatalytic property was evaluated by RhB degradation experiment under visible light irradiation. The result of experiment indicates that 10 wt% g-C3N4 composite had the best catalytic performance. The composite catalyst’s special structure enhanced the contact region between BiVO4 and g-C3N4 nanocrystals and enhanced the interaction between the chemical bands. g-C3N4 nanocrystals reduce the charge transfer distance, inhibit the photoinduced electron hole pair, and improve the composites photocatalytic activity. The photocatalyst has excellent photocatalytic properties and can degrade almost all of MB and RhB. The experimental results show that the catalyst has good stability and can be reused many times. The photocatalytic mechanism was proved by experiments and elaborated.

Ultrathin g-C3N4 nanosheet with hierarchical pores and desirable energy band for highly efficient H2O2 production

H2O2 production through photocatalysis has been considered as a sustainable technique. Here, we report ultrathin g-C3N4 nanosheets with hierarchical pores and desirable energy band for high-efficiency photocatalytic H2O2 production. The resultant catalyst showing an ultra-high H2O2 production rate of 1083 μmol g−1 h−1, which is about seven times higher than that of bulk g-C3N4 and represents one of the most active photocatalysts for H2O2 production. DFT calculation and experimental studies revealed that the suitable energy band structure achieved by a phosphorus doping in g-C3N4 leading to the efficient yielding two-electron reduction of O2 to form H2O2. Meanwhile, the particular morphology provided a large accessible surface area, multi-mass transport channels and short charge transfer distance. The synergy effect of desirable energy band and hierarchical porous nanosheets bring the excellent photocatalytic activity. In addition, the simple preparation procedure and the non-metal properties make it have great potential for the practical application.

Advances in molecular engineering of organic-inorganic/inorganic halide perovskites: Photochemical properties behind the energy conversion ability

Here, molecular engineering of the organic-inorganic/inorganic halide perovskites indicates the role of cation, anion and halide components on the efficiency of the perovskite solar cells (PVSCs). The frontier molecular orbitals alignment of the ABX3 perovskites (A = Im; Imidazolium, Az; Azetidinium, Hy; Hydrazinium, Cs, Rb, Tl, B = Pb, Sn, Ge, X = Br, Cl, I) showed a balanced electron-hole transfer. The cation and halide ion are the main parts of the charge transfer from the dynamic viewpoint, while the exciton formation/dissociation rates, Rd/Ra, are mainly affected by BX3 anion. In addition to Cs+ and Rb+, Im+-based perovskites show an effective charge transfer distance and electron-hole (e-h) overlap, which makes them good excitation modes. I-based perovskites represent a higher response to the electric field, originated from their less electronic chemical harness. According to final efficiency, Cs+, Rb+, and Az+-based perovskites are introduced as the best photosensitizers.