Improved Charge Separation Efficiency Research Articles

Novel CQDs/BiOI Microspheres with Gradient Oxygen Vacancies for Efficient Photocatalytic Performance Boosting by the Synergism of Reactive Oxygen and Iodine Species

AbstractThe synergy of reactive oxidative species (ROSs: ⋅OH, ⋅O2− and 1O2) and reactive iodine species (RISs: ⋅I and ⋅I2−) is conclusive to driving organic pollutant degradation in various aquatic environments. Over the past years, rational design of Vis‐NIR responsive photocatalyst with enhanced photocatalytic performance has attracted drawing attention. Herein, CQDs/BiOI composites with up‐conversion photoluminescence (UCPL) properties and oxygen vacancies was constructed for tetracycline (TC) and oxytetracycline (OTC) degradation. The apparent kinetic constant of the 4‐CQDs/BiOI is 2.13 and 2.38 times on pure BiOI. The excellent photodegradation efficiency can be attributed to the enhanced light absorption originated from the up‐conversion property and improved charge separation efficiency. Furthermore, the iodine free radicals (⋅I) and superoxide free radicals (⋅O2−) played a crucial role in the photodegradation procedure. I− from BiOI could be partially oxidized to form ⋅I. At the same time, the electron capture traps formed by Oxygen vacancies can promote the production of ⋅O2−. Remarkably, the removal efficiency of TC and OTC was still maintained at 80 % by 4‐CQDs/BiOI under different water quality conditions due to the synergy of ⋅O2− with ⋅I. This work sheds light on a new treatment for the synergistic degradation of pollutants in complex water by RISs and ROSs.

Visible light driven Z-scheme α-MnO2 (1D)/Bi7O9I3 (2D) heterojunction photocatalyst for efficient degradation of bisphenol A in water

Z-scheme heterojunctions are gaining attention for their outstanding photocatalytic performance in degrading organic pollutants due to improved charge separation efficiency. In view of this, the present study is focused on the synthesis of novel 3D α-MnO2/Bi7O9I3 (MB) nanocomposites heterojunctions of varying α-MnO2 contents via facile in-situ chemical precipitation method at room temperature. Under optimum conditions, MB4 (comprising 485 mg of α-MnO2) exhibited exceptional performance, achieving about 97.5% of bisphenol A (BPA) degradation in 80 mins with a degradation rate constant of 0.08354 min−1. Such superior performance is attributed to efficient interfacial integration and charge separation, validated through various characterization techniques. Further, MB4 heterojunction facilitated Z-scheme electron-hole pair transfer and exhibited an augmented specific surface area. The active species involved in the degradation of BPA were identified as •O2– and •OH in scavenging experiments and supported by findings based on EPR. Additionally, degradation pathways and plausible BPA intermediates have been proposed based on LC-MS/MS studies. Furthermore, with an impressive mineralization rate (89.5%), the toxicity study unveiled less harmful intermediates than the parent compound BPA. MB4 photocatalyst also exhibited commendable stability, as evidenced by its studies based on five reuse cycles with 92.9% efficiency. In essence, visible-light-driven Z-scheme α-MnO2/Bi7O9I3 heterojunction photocatalyst offered a simple and sustainable approach for producing environmentally friendly materials, underscoring its potential in the removal of BPA in water and wastewater treatment.

Bulk and interface engineering with the combined addition of Na+ and E5+ (E = Nb5+, Ta5+) in the design of hematite photoanodes

In this letter, the synergistic effects of multiple element modification through a single polymeric precursor solution in hematite-based photoanodes using Na/Nb and Na/Ta as dopants are evaluated. Linear sweep voltammetry curves showed that the photoelectrochemical response was improved after Na/Nb (or Ta) addition. In both circumstances, an anodic shift (∼200 mV) in the onset potential was noticeable due to surface states created after Nb5+/Ta5+ segregation. The energetic loss caused by Nb (and Ta) segregation was partially restituted by NiFeOx addition due to the passivation of surface states, acting as recombination centers created by pentavalent modifiers. These combined modifications brought a three and four-fold increase for Na0.1HemNb1.5 NiFeOx and Na0.1HemTa1.0NiFeOx respectively. Charge carrier dynamics analysis studied by intensity modulated photocurrent spectroscopy revealed that the PEC enhancement in both systems is mainly associated with improved charge separation efficiency.

Modelling Photocatalytic N2 Reduction: Where We Stand and Where We Are Going.

Artificial ammonia synthesis via the Haber-Bosch process is environmentally problematic due to the high energy consumption and corresponding CO2 emissions, produced during the reaction and before hand in hydrogen production upon methane steam reforming. Photocatalytic nitrogen fixation as a greener alternative to the conventional Haber-Bosch process enables us to perform nitrogen reduction reaction (NRR) under mild conditions, harnessing light as the energy source. Herein, we systematically review first-principles calculations used to determine the electronic/optical properties of photocatalysts, N2 adsorption and to expound possible NRR mechanisms. The most commonly studied photocatalysts for nitrogen fixation are usually modified with dopants, defects, co-catalysts and Z-scheme heterojunctions to prevent charge carrier recombination, improve charge separation efficiency and adjust a band gap to for utilizing a broader light spectrum. Most studies at the atomistic level of modeling are grounded upon DFT calculations, wholly foregoing excitation effects paramount in photocatalysis. Hence, there is a dire need to consider methods beyond DFT to study the excited state properties more accurately. Furthermore, a few studies have been examined, which include higher level kinetics and macroscale simulations. Ultimately, we show there is still ample room for improvement with regard to first principles calculations and their integration in multiscale models.

Adjusting photocatalytic hydrogen production of TiO2 hollow nanospheres through nitrogen-induced shallow trapping levels

N-doped titanium dioxide (TiO[Formula: see text] hollow nanospheres with abundant oxygen vacancies were successfully synthesized by coupling urea treatment and annealing in an N2 atmosphere. The pristine TiO2 hollow nanospheres exhibit a shallow donor level for electron trapping, while the urea treatment generates a N 2p acceptor level for hole trapping. After annealing in N2, the sufficient N atoms generate abundant oxygen vacancies for trapping electrons, resulting in further improved charge separation efficiency. The N-doped TiO2 exhibits the highest H2 evolution rate, reaching 2867[Formula: see text][Formula: see text]mol[Formula: see text]g[Formula: see text][Formula: see text]h[Formula: see text], which is six times higher than that of pristine TiO2 hollow nanospheres. The introduction of oxygen vacancies by interstitial N provides a promising way to improve the photocatalysis activity of photocatalysts.

Interfacial coupling of CuFe2O4 induced hotspots over self-assembled g-C3N4 nanosheets as an efficient photocatalytic bacterial disinfectant

Most bacterial disinfectants contain high levels of extremely toxic and environmental hazardous chemicals, which pose a significant threat to the ecosystem. Semiconductor photocatalysis exhibits attractive prospects as an emerging greener technology for waste water disinfection. However, the fast recombination of charge carriers limits its practical application. Herein, self-assembled polymeric feather-like g-C3N4 (GCN) nanosheets modified with ferromagnetic CuFe2O4 (CFO) nanospheres were successfully applied as a reusable visible light photocatalytic disinfectant. As expected, the g-C3N4/CuFe2O4 (GCF) nanohybrid displayed superior photocatalytic inactivation efficiency of 0.157log within 120 min towards Escherichia coli DH5α (E. coli) compared with pristine GCN and CFO. The characterization results revealed the synergistic heterostructure interfaces, high surface area, and the transformative self-assembly of GCN to feather-like structure providing a rich active site for improved charge separation efficiency, and wide spectral response, therefore the superior performance of GCF. The radical trapping assay proclaimed that both O2•- and •OH radical played major role in the photocatalytic inactivation among the other reactive oxygen species (ROS). Furthermore, the chemical oxygen demand (COD), protein estimation, and DNA estimation assay results validated the cell damage caused by the photocatalyst. Besides that, GCN showed applicability in real-time wastewater samples with improved efficiency than in the saline solution. The excellent magnetic characteristics facilitated the recycling of the catalyst with insignificant leaching, magnetic induction, and distinguished separation. The results of this work signify the well-designed GCF as a high-performance and reusable photocatalyst for real-world pathogenic bacterial disinfection operations.

Theoretical study of the effect of D-A type polymer donors on the performance of Y6-based organic solar cells

Non-fullerene organic solar cells (OSCs) based on Y6 molecule have developed rapidly in recent years, and the power conversion efficiency (PCE) varies greatly when the OSC device constructed by Y6 and donor molecules with small structural difference. In this work, the influence of six donor-acceptor (D-A) polymer donors on Y6-based OSCs were focused. The ground-state properties (planarity, frontier molecular orbital energy levels, driving force), excited-state properties of donors (primary indicators, Coulomb attraction) and donor/acceptor interfaces (Frenkel excitation (FE) and charge transfer (CT) states, electron coupling and charge separation rates) were discussed. The results show that symmetrical alkyl chains in the acceptor unit is favorable for maintaining planarity of molecule, while fluorination induces twisting in the thiophene bridge and acceptor unit. And the investigated high-performance molecules have desirable driving force, smaller Coulomb attraction and significant degree of holes and electrons delocalization. Also, the highest-performance system has multiple charge transfer pathways, which can improve charge separation efficiency. At the same time, high-performance systems often have better planarity and more favorable substituent positions. The high-performance donor/Y6 systems have more advantage in charge separation than the low-performance systems. This work provides a fundamental understanding of the impact of D-A type donor materials on the cell performance and theoretical guidance for further optimization of polymer donor materials in Y6-based OSCs.

Schottky junction enhanced H2 evolution for graphitic carbon nitride-NiS composite photocatalysts

As one of the most promising photocatalysts for H2 evolution, graphitic carbon nitride (CN) has many appealing attributes. However, the activity of pristine CN remains unsatisfactory due to severe charge carrier recombination and lack of active sites. In this study, we report a two-step approach for the synthesis of CN nanotubes (TCN) loaded with NiS nanoparticles. The resulting composite photocatalysts gave a H2 evolution rate of 752.9 μmol g−1 h−1, which is 42.3 times higher compared to the pristine CN photocatalyst. Experimental and simulation results showed that the Schottky junction which was formed between TCN and NiS was key to achieving high activity. This is because the formation of Schottky junction prevented the backflow of electrons from NiS to TCN, which improved charge separation efficiency. More importantly, it also led to the accumulation of electrons on NiS, which significantly weakened the SH bond, such that the intermediate hydrogen species desorbed more easily from NiS surface to promote H2 evolution activity.

Accelerated inter/intra-layer electron transport by asymmetric metal site induced delocalization effect for photoelectrocatalytic water oxidation

Charge transfer at the primary catalyst, co-catalyst, and solution interface is fundamental for photoelectrocatalytic water oxidation. In this paper, we propose a strategy to create a co-catalyst comprised of zinc-cobalt diatomic sites on a nitrogen-doped carbon matrix (CoZn-NC) and load it on BiVO4, called CoZn-NC/BVO. Asymmetrically-doped nitrogen-carbon layer materials of Zn and Co (CoZn-NC) can enable the unrestricted mobility of lone pairs of electrons in metals upon exposure to light irradiation, which results in interlayer polarization and electron delocalization effects, leading to improved charge separation efficiency. Furthermore, due to the synergistic effect of bimetallic doping, not only does the intralayer polarized electric field formed on the surface of CoZn-NC improve the charge injection efficiency, but it also modulates the d-band center of the active site Co, thus reducing the Gibbs free energy of the reaction. The results show that the oxygen reduction reaction of CoZn-NC/BVO is excellent, with a photocurrent density of 5.84 mA cm−2 at 1.23 V vs. RHE, which is 4.35 and 2.1 times higher than that of BiVO4 and Co-NC/BVO, respectively. The charge separation and charge injection efficiencies were also significantly higher, at 84.89 % and 91.97 %, respectively. Overall, the proposed co-catalyst of CoZn-NC/BVO shows great potential in photoelectrocatalytic water oxidation and provides a valuable contribution to the field.

Principle of CoS2/ZnIn2S4 heterostructure effect and its mechanism of action in a visible light-catalyzed antibacterial process

The development of visible-light-driven catalytic antimicrobial technology is a significant challenge. In this study, heterojunctions were constructed for the appropriate modification of semiconductor-based photocatalysts. A simple hydrothermal method was used for material reconstruction, and smaller CoS2 nanoparticles were deposited and in situ grown on two-dimensional nanoflower-like ZnIn2S4 carriers to form CoS2/ZnIn2S4 (CS/ZIS) Schottky heterojunctions. Systematic study via characterization techniques and density functional theory calculations indicated that the excellent photocatalytic activity of CS/ZIS stemmed from the solid interfacial coupling between the two solid-phase materials. These materials acted as co-catalysts to increase the number of active reaction sites, enhance charge transfer, drive unidirectional electron movement, and improve charge separation efficiency, which effectively facilitated the production of reactive oxygen species (ROS). The optimized CS/ZIS heterojunction exhibited excellent performance for the efficient photocatalytic degradation of organic matter and inactivation of Escherichia coli (E. coli) compared with the ZnIn2S4 photocatalyst. Moreover, the antibacterial mechanism of the heterojunction photocatalyst and the extent of damage to the cell membrane and internal cytoplasm were explored by performing various assays. It was demonstrated that superoxide radicals are the predominant active species and multiple ROS act together to cause oxidative stress damage and cell inactivation.

Near-infrared light-assisted dual-modal photoelectrochemical and photo-fuel-cell-driven self-powered biosensor for detection of miRNA-21 in living cancer cells

The advancement of the dual-modal photoelectrochemical (PEC) and photo-fuel-cell-driven self-powered biosensor (PFC-SPB) with the aid of near-infrared light (NIR) irradiation can present a robust sensing strategy for the feasible, sensitive detection of cancer biomarkers in living cancer cells. In this work, a novel NIR-assisted dual-modal PEC and PFC-SPB is proposed for the sensitive inspection of miRNA-21 based on a 2D/2D p-n heterojunction, which is prepared by the in-situ growth of zinc indium sulfide nanosheets (ZnIn2S4 NSs) over the 2D zinc porphyrin-based metal–organic frameworks using meso-tetra (4-carboxyphenyl) porphyrin as ligand (denoted as ZnIn2S4@Zn-TCPP). Benefiting the integration of the features of ZnIn2S4 and Zn-TCPP, the developed p-n heterojunction demonstrates rich element vacancies, regulated NIR absorption, and improved charge separation efficiency of the photogenerated electron–hole pairs. Thus, the ZnIn2S4@Zn-TCPP photoelectrode affords the boosted photoelectric conversion efficiency and large output voltage as well as large amounts of anchored complementary DNA strand due to the comprehensive interaction. The constructed dual-modal PEC and PFC-SPB, respectively, exhibit an ultralow limit of detection (LOD) of 0.43 and 0.71 fM toward miRNA-21 within a range of 1 fM to 1 nM, along with the other superior sensing abilities. The PFC-driven self-powered biosensor also shows a great potential in the selective detection of miRNA-21 contained in living cancer cells. The present work provides an NIR-assisted dual-modal biosensing strategy for the efficient analysis of cancer biomarkers in vitro.

Symbiotic MoO3-SrTiO3 Heterostructured Nanocatalysts for Sustainable Hydrogen Energy: Combined Experimental and Theoretical Simulations.

Highly efficient Z-scheme MoO3-SrTiO3 heterostructured nanocatalytic systems were engineered via a sol-gel chemical route and exploited in green H2 energy synthesis via overall water splitting. The optical and electronic investigations corroborated the enhancement of the optoelectronic properties of SrTiO3 after the incorporation of MoO3. Emergence of the interfacial charge transfer between SrTiO3 and MoO3 is the driving force, which synergistically triggered the catalytic efficiency of MoO3-SrTiO3 heterostructures. The substitution of Ti4+ by Mo6+ ions led to the suppression of Ti3+ mid-gap states, as the potential involved in the Mo6+/Mo5+ reduction is higher than that in Ti4+/Ti3+. Theoretical studies were employed in order to comprehend the mechanism behind the advancement in the catalytic activity of MoO3-SrTiO3 porous heterostructures, which also possessed a higher surface area. 2% MoO3-SrTiO3 exhibited the optimum catalytic response toward H2 evolution via photochemical, electrochemical, and photo-electrochemical water splitting. 2% MoO3-SrTiO3 evolved H2 at the fourfold higher rate than SrTiO3 with phenomenal 16.06% AQY during photochemical water splitting and photo-degraded MB dye at nearly 88% against the 42% degradation in SrTiO3-led photocatalysis. Electrochemical and photo-electrochemical investigations also manifested the superiority of 2% MoO3-SrTiO3 toward HER, as it exhibited accelerated current and photocurrent densities of 25.02 and 27.45 mA/cm2, respectively, at the 1 V potential. EIS studies demonstrated the improved charge separation efficiency of MoO3-SrTiO3 heterostructures. This work highlights the multi-dimensional approach of obtaining green H2 energy as the sustainable energy source using MoO3@SrTiO3 heterostructures.

Broad-bandgap porous graphitic carbon nitride with nitrogen vacancies and oxygen doping for efficient visible-light photocatalytic degradation of antibiotics

Effective degradation methods are required to address the issue of antibiotics as organic pollutants in water resources. Herein, a two-stage thermal treatment method was used to prepare porous graphitic carbon nitride (g-C3N4) modified with nitrogen vacancies and oxygen doping at the N–(C)3 position and deep in the g-C3N4 framework. Compared with bulk g-C3N4 (BCN) (7 ± 1 m2/g), the modified sample (RCN-2h) possesses a larger specific surface area (224 ± 1 m2/g), a larger bandgap (by 0.19 eV), and a mid-gap state. In addition, RCN-2h shows 15.4, 11.2, and 9.5 times higher photodegradation rates than BCN for the degradation of 100% ofloxacin (OFX) (within 15 min), tetracycline (within 15 min), and sulfadiazine (within 35 min), respectively. The RCN-2h catalyst also exhibits superior stability and reusability. Systematic characterization and density functional theory calculations demonstrate that the synergistic effect of the porous structure, nitrogen vacancies, and oxygen doping in RCN-2h provides additional reaction sites, improved charge separation efficiency, and shorter diffusion paths for reactants and photogenerated charge carriers. Trapping experiments reveal that •O2− is the main active species in OFX photodegradation, and a possible photodegradation pathway is identified using liquid chromatography–mass spectrometry. Benefiting from the simplicity of synthesis methods and the superiority of elemental doping, carbon nitride materials with functional synergy have great potential for environmental applications.

Enhanced photocatalytic reduction of CO2 over pg-C3N4-supported TiO2 nanoparticles with Ag modification

Photoreduction of CO2 has been a promising route to decrease CO2 emission and obtain valuable fuels or chemical raw materials, but it still faces tremendous challenge. Composite catalyst fabricated with TiO2 and g-C3N4 might exhibit great competitive advantages, due to their potential application prospects in the field of photocatalysis. Herein, we prepared a novel pg-C3N4/Ag-TiO2 composite catalyst by using the porous defective g-C3N4 (pg-C3N4) and Ag doped TiO2, and a three-component S-scheme heterojunction had been built. Compared to individual g-C3N4 or Ag-TiO2, the synthesized pg-C3N4/Ag-TiO2 material demonstrates significantly increased photocatalytic activity for the reduction of CO2 and the AQE reaches 2.364%. In addition to improved charge separation efficiency of S-scheme heterojunctions, increased surface area of the catalyst could also be responsible for the enhanced photocatalytic performance. Experimental and computational reveals that when Ag is added to TiO2, its work function is adjusted, and electrons are transferred in a different direction, promoting the formation of S-scheme heterojunctions.

Photobreeding Heterojunction on Semiconductor Materials for Enhanced Photocatalysis

AbstractConstruction of heterojunctions to photocatalysts is one of the most promising approaches to improve charge separation efficiency; however, the established constructing processes usually require high‐temperature conditions and/or the adding of highly concentrated or expensive exotic species, and the improvement of effective contact and charge exchange between heterojunction components remains a problem. This work proposes an unprecedented “photobreeding” method and realizes the direct growth of Zn nanowires and Mott–Schottky heterojunctions from ZnS or viologen‐coated ZnS microspheres through a photochemical reaction at room temperature without external species, while demonstrating the hypothesis proposed 140 years ago on the formation of Zn in the photochromic process of ZnS. After photobreeding of the heterojunctions, the hydrogen production efficiency of the photocatalysts increases by 2 orders of magnitude. This inexpensive, facile and efficient synthetic method will find applications in H2 production, organic synthesis, CO2 reduction, nitrogen fixation, and so on.

Visible light-driven photocatalytic degradation of fluoroquinolone drugs in water over plasmonic Ag/ZnNb2O6@SC3N4 indirect Z-scheme nanostructures

The fabrication of visible light responsive heterojunction photocatalyst with efficient charge separation and transfer is an important quest in the exploitation of photocatalysis for environmental remediation. In this work, a ternary heterostructure comprising of zinc niobate (ZnNb2O6) coupled with sulphur-doped graphitic carbon nitride (SC3N4) and decorated with varying loadings of silver nanoparticles (Ag NPs) was obtained using ultrasonic synthesis. The photocatalysts were characterized extensively using various microscopic, spectroscopic, and electrochemical analytical techniques. The 5 wt%Ag/ZnNb2O6 @SC3N4 heterojunction showed the highest degradation efficiencies towards the antibiotic drugs; levofloxacin (LVF, 94.6 % removal) and ofloxacin (OFX, 98.0 % removal) in just 60 min of visible light irradiation. This activity is nearly 5 times and 3.5 times higher than that over ZnNb2O6 @SC3N4 for LVF and OFX, respectively, which indicates the importance of incorporating the Ag NPs towards better visible utilization, improved charge separation efficiency and lower charge transfer resistance. The influence of pH, photocatalyst dose and initial concentration of pollutant were investigated. Finally, a typical Ag NPs mediated indirect Z-Scheme charge transfer mechanism was proposed to describe the formation of the reactive species and subsequent degradation of the pollutants. This work demonstrates a systematic design of simple but efficient photocatalytic nanocomposites with the capability to ameliorate a wide variety of fluoroquinolone drugs, which is significant towards pharmaceutical pollution mitigation.

Investigation on structural, optical and electrical properties of BiFeO3:ZnO nano–micro particles–matrix composite

A new class of materials called matrix-nano composites has the ability to meet the needs of modern advanced applications and technology. To prepare the BiFeO3:ZnO composite, BiFeO3 nanoparticles were prepared using a low–cost sol–gel method, to which ZnO in its micron-sized form was added in varying concentrations of 5%, 10%, and 15%. The structural, morphological, and optical properties of the pure and composite materials were characterized using XRD, FESEM, EDAX, PL spectra, and UV-Visible spectroscopy. The dielectric properties of the pristine and composites were investigated at room temperature. The a.c. conductivity fit with Jonscher's power law and CBH model described the charge conduction behaviour in all pure and composite materials. The temperature-dependent dielectric and loss measurements showed a temperature dependent relaxation process. UV–vis and PL characterization show that the composite materials exhibited improved charge separation efficiency and wider band gaps with increasing BFO content.

Core-shell structured FeOCl/Bi5O7Br nanocrystals for visible-light-driven photocatalyst in aqueous solution

Herein in this work, we constructed a one-dimensional iron oxychloride (FeOCl) needles embedded on the surface of Bi5O7Br squares to construct a core-shell structured FeOCl/Bi5O7Br heterojunction. The as-synthesized samples were systematically characterized by various analytical techniques which confirmed the successful formation of core-shell FeOCl/Bi5O7Br nanocrystals. The XRD results confirmed that the FeOCl and Bi5O7Br existed in the semi-crystalline nature due to the confined synthesis procedure. The UV-DRS results confirmed that the core-shell structure significantly improved visible light absorption, which leads to a drop-in band gap energy of the FeOCl/Bi5O7Br heterojunction photocatalyst. The improved charge separation efficiency was further confirmed by the ESR and photoluminescence studies. The FeOCl/Bi5O7Br heterojunction photocatalyst was further applied towards the degradation of tetracycline under visible light through batch experiments. Based on the radical trapping experiments, ESR studies, and photocurrent measurements, the h+, •OH, and •O2− played a major role in the tetracycline photodegradation process. Finally, it was established that novel, recyclable photocatalyst was made, which underwent up a brand-new pathway for the degradation of various emerging pollutants. Meanwhile, this work may play an essential role in environmental conservation and sustainable development.

Partial disorder structured BiOI atomic layers boosting excitons dissociation for photocatalytic CO2 reduction and pollutant removal

Owing to atomic-thin thickness, reduced dielectric screening will usually happen in 2D atomic layers and lead to the formation of strong exciton effect, which is not energetically for some photocatalytic reactions. In this work, a scalable fast synthesis strategy is developed to fabricate BiOI atomic layers with partial disorder area (BiOI-D) at room temperature, as observed by HAADF-STEM image. This order–disorder interface in BiOI atomic layers favors boosting excitons dissociation to free charge carriers. Due to the atomic-thin thickness for rapid bulk charge diffusion and order–disorder interface for excitons dissociation, this BiOI-D atomic layers display greatly improved charge separation efficiency compared to BiOI nanosheets, thus contribute to enhanced photocatalytic activity for pollutants degradation and CO2 reduction. Compared to BiOI nanosheets, a 12.5 times increased CO2 photoreduction activity can be realized over BiOI-D atomic layers, with the CO generation rate of 15.1 μmol g−1 in 5 h. Profiting from the order–disorder interface, CO2 activation energy barrier can be lowered and rate-limiting step energy barrier for COOH* formation is decreased from 0.67 to 0.34 eV.

Phase Engineering of 2D Violet/Black Phosphorus Heterostructure for Enhanced Photocatalytic Hydrogen Evolution

Rapid charge recombination has limited the application of black phosphorus (BP) as a visible light‐responsive photocatalyst. Violet phosphorus (VP), another 2D phosphorus allotrope, has drawn extensive attention for its excellent semiconductor property. However, its photocatalytic activity for hydrogen (H2) evolution is yet to be studied. Herein, a VP/BP heterostructure using a phase engineering strategy is constructed, wherein few‐layered VP is interlaced with BP to create a well‐matched heterophase interface by virtue of their identical chemical compositions and different crystal phases. Experimental and theoretical calculations reveal that VP and BP exhibit strong interaction at the heterophase interface, which is found effective in accelerating photogenerated electron transfer from BP to VP for improved charge separation efficiency. After being decorated with a Rh cocatalyst, the VP/BP heterostructure with utilization of visible light up to 700 nm shows ≈3‐ and 210‐times greater photocatalytic H2 evolution activity with respect to its counterparts. This study highlights feasibility of phase engineering and provides an alternative strategy in promoting charge separation as well as performance of photocatalyst.