Superior Photocatalytic Activity Research Articles

Boosting Solar-Driven CO2 Conversion to Ethanol via Single-Atom Catalyst with Defected Low-Coordination Cu-N2 Motif.

In this paper,we report a high-performance carbon nitride supported Cu single-atom catalyst featuring defected low-coordination Cu-N2 motif (Cu-N2-V). Lead many recently reported photocatalysts and its Cu-N3 and Cu-N4 counterparts, Cu-N2-V exhibits superior photocatalytic activity for CO2 reduction to ethanol, delivering 69.8 μmol g-1 h-1 ethanol production rate, 97.8% electron-based ethanol selectivity, and a yield of ~10 times higher than Cu-N3 and Cu-N4. Revealed by the extensive experimental investigation combined with the DFT calculation, the superior photoactivity of Cu-N2-V stems from its unique defected Cu-N2 configuration. Firstly, Cu in Cu-N2-V exist in Cu+/Cu2+ dual valence states, although predominantly in Cu+. The Cu+ sites support CO2 activation and the Cu+/Cu2+ sites are conducive for strong *CO adsorption and subsequent *CO-*CO dimerization enabling C-C coupling. Secondly, the Cu sites in Cu-N2-V are rich in electrons and thus highly active. Together they dictate the rate-determining step on CO2 photoreduction to ethanol and lower the Gibbs free energy change. Furthermore, the defected configuration also promotes light adsorption and charge separation efficiency. Collectively, these make Cu-N2-V an effective and high-performance catalyst for solar-driven CO2 conversion to ethanol. This study also reveals the valence state change of Cu in Cu-N2-V during the CO2 photoreduction reaction.

Fabrication of 2D/2D InVO4/BiVO4 Heterojunction with Synergistic Effects for Enhanced Photocatalytic Degradation and Photoelectrochemical Applications

In this work, we report a novel 2D/2D InVO4/BiVO4 heterojunction nanocomposite constructed through a simple hydrothermal approach. The morphological analysis demonstrated that BiVO4 nanoflakes to be anchored on the surface of InVO4 nanosheets. The InVO4/BiVO4 heterojunction nanocomposite displayed increased light absorption promoting their visible light harvesting. The photoactivity of the prepared InVO4/BiVO4 heterojunction was explored for the degradation of tetracycline (TC) under light treatment. InVO4/BiVO4 heterojunction exhibited superior photocatalytic activity than that of bare InVO4 and BiVO4. The as-prepared InVO4/BiVO4 heterojunction photoanodes achieved a higher photocurrent density of 60 μA/cm2 under illumination in 0.5 M Na2SO4 electrolyte. The enhanced photoelectrochemical performance is attributed to the synergistic effect and interface formation between InVO4 and BiVO4 and can effectively promote the charge separation and transfer of photoinduced carriers in heterojunction.

Recent Developments of Nanostructured Photocatalysts Based on Semiconducting Chalcogenides for Organic Reactions

Abstract:: The earth-abundant metal chalcogenide is a highly versatile semiconductor with unique electronic and optical properties that seem to outperform the photocatalytic properties of metal oxides and metal nanoparticles. For ages, researchers are reaping the benefits of its photocatalytic properties in numerous reactions. However, the high charge recombination rates, poor compositional stability, and a smaller number of catalytically active sites restrict its application. The development of different kinds of heterojunctions by the combination of metal-chalcogenides with other conducting and semiconducting materials like metal oxides, metal nanoparticles, g-C3N4, single-atom catalysts, and MOF results in superior photocatalytic activity. This review provides insight into the various classes of metal-chalcogenide-based heterostructures and their application in various organic transformations. A brief overview of the synergistic properties arising from the development of such heterostructures helps to understand the surface interactions so that highly stable, efficient, and selective metal-chalcogenide-based heterostructures can be developed for industrially important photocatalytic organic transformations. This review also describes the role of mediators in boosting the stability and catalytic efficiency of the metal chalcogenides. Moreover, a thorough emphasis on the morphological impact of photocatalysts in various reactions will help with the development of metal chalcogenide heterostructures with tunable morphology and bandgap.

Surface-Grafted Single-Atomic Pt-Nx Complex with a Precisely Regulating Coordination Sphere for Efficient Electron Acceptor-Inducing Interfacial Electron Transfer.

Based on the electron-withdrawing effect of the Pt(bpy)Cl2 molecule, a simple post-modification amide reaction was firstly used to graft it onto the surface of NH2-MIL-125, which formed a highly efficient electron acceptor that induced the conversion of the photoinduced charge migration pathway from internal BDC→TiOx migration to external BDC→PtNx migration, significantly improving the efficiency of photoinduced electron transfer and separation. Furthermore, precise control over the first coordination sphere of Pt single atoms was achieved using further post-modification with additional bipyridine to investigate the effect of Pt-Nx coordination numbers on reaction activity. The as-synthesized NML-PtN2 exhibited superior photocatalytic hydrogen evolution activity of 7.608 mmol g-1 h-1, a remarkable improvement of 225 and 2.26 times compared to pristine NH2-MIL-125 and NML-PtN4, respectively. In addition, the superior apparent quantum yield of 4.01% (390 nm) and turnover frequency of 190.3 h-1 (0.78 wt% Pt SA; 129 times compared to Pt nanoparticles/NML) revealed the high solar utilization efficiency and hydrogen evolution activity of the material. And macroscopic color changes caused by the transition of carrier migration paths was first observed. It holds profound significance for the design of MOF-Molecule catalysts with efficient charge carrier separation and precise regulation of single-atom coordination sphere.

Surface‐Grafted Single‐Atomic Pt‐Nx Complex with a Precisely Regulating Coordination Sphere for Efficient Electron Acceptor‐Inducing Interfacial Electron Transfer

Based on the electron‐withdrawing effect of the Pt(bpy)Cl2 molecule, a simple post‐modification amide reaction was firstly used to graft it onto the surface of NH2‐MIL‐125, which formed a highly efficient electron acceptor that induced the conversion of the photoinduced charge migration pathway from internal BDC→TiOx migration to external BDC→PtNx migration, significantly improving the efficiency of photoinduced electron transfer and separation. Furthermore, precise control over the first coordination sphere of Pt single atoms was achieved using further post‐modification with additional bipyridine to investigate the effect of Pt‐Nx coordination numbers on reaction activity. The as‐synthesized NML‐PtN2 exhibited superior photocatalytic hydrogen evolution activity of 7.608 mmol g−1 h−1, a remarkable improvement of 225 and 2.26 times compared to pristine NH2‐MIL‐125 and NML‐PtN4, respectively. In addition, the superior apparent quantum yield of 4.01% (390 nm) and turnover frequency of 190.3 h−1 (0.78 wt% Pt SA; 129 times compared to Pt nanoparticles/NML) revealed the high solar utilization efficiency and hydrogen evolution activity of the material. And macroscopic color changes caused by the transition of carrier migration paths was first observed. It holds profound significance for the design of MOF‐Molecule catalysts with efficient charge carrier separation and precise regulation of single‐atom coordination sphere.

Reduced Work Function in Anatase ⟨101⟩ TiO2 Films Self-Doped by O-Vacancy-Dependent Ti3+ Bonds Controlling the Photocatalytic Dye Degradation Performance.

TiO2 has the proven capability of catalytically decomposing pollutants under light illumination, thereby embracing potential applications in wastewater management. The photocatalytic dye degradation activity is largely controlled by the optical band gap that dictates the extent of electron-hole pair generation via photon absorption, and the recombination kinetics of charges. In this context, the material's work function governs how easily the charge carriers can be transferred at the dye-adsorbed photocatalytically active sites. Accordingly, nanocrystalline TiO2 thin films are grown in the anatase phase with ⟨101⟩ orientation, using RF magnetron sputtering at 200 °C. Besides studying the film's structural morphology, optical band gap, and elemental composition, the electronic properties are extensively investigated. The work function of the material was controlled by varying the O-vacancy-dependent Ti3+ bonding configuration in the network. It has been demonstrated how the photocatalytic methylene blue dye degradation activity of the nanocrystalline TiO2 films of predominantly the anatase phase improves on reducing the sputtering pressure during deposition. At a low deposition pressure of 20 mTorr, a low work function of ∼4.2 eV of the film, resulting from the formation of a Ti3+-bond through the O vacancies in the network, potentially increases its carrier lifetime and delivers the superior photocatalytic activity (∼82.7% dye degradation with a rate constant of k ∼ 0.0073 min-1) via silently facilitating fast electron transfer from the photocatalyst to the dye in the aqueous solution. The higher stoichiometric film prepared at p = 40 mTorr exhibits an inferior photocatalytic activity (∼20.4% dye degradation with a rate constant of k ∼ 0.0009 min-1), as retarded by its higher work function of ∼4.62 eV, despite retaining a relatively low band gap. Thus, without using any heterojunction or extrinsically doped photocatalyst, the dye degradation can be controlled simply by reducing the work function of nanocrystalline TiO2 thin films via controlling the O-vacancy-dependent Ti3+ bonding in its self-doped network.

One pot synthesis of multi-functional B doped g-C3N4-praseodymium oxide nanocomposites for colorimetric detection of Hg2+ ion and solar photocatalytic removal of toxic water pollutants

A novel praseodymium oxide-boron co-doped graphitic carbon nitride composite was synthesized via one-step solid-state thermal condensation of urea, orthoboric acid and praseodymium nitrate precursors. The prepared composites were characterized by various methods. All the prepared composites demonstrated multi-functional activities towards peroxidase-mimetic based colorimetric detection of Hg2+ ions and superior photocatalytic efficiency towards photodegradation of textile colorants, photoreduction of hexavalent chromium and nitro aromatics like para-nitro phenol (PNP) and para-nitro aniline (PNA). The superior photocatalytic activity can be attributed to the formation of type II heterojunction which facilitates charge separation and increases the lifetime of photogenerated charge pairs. As evident from the scavenger studies, these charge pairs are involved in the formation of superoxide and hydroxyl radicals. The superior activity of the optimum composite can be attributed to the porous flaky morphology, decreased optical band gap, heterojunction mediated charge separation, and praseodymium oxide's conductive nature. A linear range of about 0.25–800 nM of Hg2+ ions can be detected with a limit of detection (LOD) of 42.4 nM using the colorimetric strategy. The as-synthesized composite is thus a unique, efficient, economically viable, and excellent candidate for detecting and degrading various hazardous water pollutants.

Novel in-situ Ag-decorated trithiocyanuric acid polymer with superior visible light photocatalytic activity

A novel Ag-decorated trithiocyanuric acid polymer (Ag-TTCA) was fabricated via a photocatalytic reduction method based on the strong affinity between Ag ion and trithiocyanic acid (TTCA). The as-prepared photocatalysts were characterized, and the paralleled experiments were conducted on the photocatalytic oxidation of bisphenol A (BPA) to evaluate the photocatalytic activity. Compared with TTCA, Ag-TTCA has a much higher photocatalytic activity. The 0.08Ag-TTCA catalyst can remove BPA (20 mg L−1) in 240 min with a degradation efficiency as high as 96.4 %. The improved photocatalytic performance of Ag-TTCA can be attributed to the dispersed nanoparticle morphology and unique electronic structure. The dispersed nanoparticle morphology of Ag-TTCA can provide more active sites for the adsorption and degradation of pollutants. After silver modification, the light absorption threshold of TTCA is redshifted from 466 nm to 522 nm, and the corresponding band gap is reduced from 2.74 eV to 2.54 eV, which broadens the light absorption range of the photocatalyst and significantly enhances the light absorption capacity. Moreover, metal silver can trap photogenerated electrons and generate surface plasmon resonance (SPR) when illuminated by sunlight, which can effectively promote the separation of electron-hole pairs. Trapping experiment indicates that photogenerated holes, singlet oxygen and superoxide free radicals are the main active species in photocatalytic system.

Boosting solar-driven photocatalytic degradation of organic contaminants and bacterial deactivation using marigold- like Cu2O decorated g-C3N4 nanocomposite

Keeping the high efficiency in designing photocatalysts in view, the present work was aimed at the development of a heterojunction photocatalyst with boosted efficiencies, both for degradation of organic contaminants and bacterial deactivation. Heterojunction nanocomposites of g-C3N4 (GCN) and Cu2O (Cu2O /GCN-5 %, Cu2O /GCN-15 %, Cu2O/GCN-25 %, and Cu2O /GCN-50 %) were prepared by hydrothermal method and their photocatalytic performance was evaluated. XPS result confirms the surface chemical composition of nanocomposite and consistent with EDX analysis. The BET studies of Cu2O/GCN −25 % nanocomposite reveals the larger specific surface area (128.10 m2/g), compared to intact Cu2O, which facilitates more active sites on the surface. The optical bandgap energy (2.39 eV-2.58 eV) is tuned towards the visible region by loading g-C3N4 in marigold-like Cu2O. The efficient charge transfer betwixt marigold-like Cu2O and g-C3N4 was demonstrated in PL, CV, and EIS analysis. The Cu2O/GCN-25 % nanocomposite exhibits superior photocatalytic activity towards Aniline blue dye (86.4 %) and β-lactam antibiotic amoxicillin (79 %) under 100 min of sunlight irradiation. HPLC analysis further confirmed the degradation and disintegration of Amoxicillin. The probable photocatalytic mechanism was proposed and tested through a radical scavenger experiment. It was found that ●OH radicals significantly take part in the photodegradation. In addition, the bactericidal activities of Cu2O/GCN-25 % nanocomposite was determined. The highest bactericidal activity was observed for Bacillus subtilis (26 mm). Hence, the marigold-like Cu2O/GCN-25 % nanocomposite is a feasible material for the degradation of dyeing and pharmaceutical industrial effluents as well as bacterial growth inhibition.

Construction of CdIn2S4/ZnSn(OH)6 heterojunctions for efficient photocatalytic hydrogen generation

CdIn2S4 nanosheets ornamented ZnSn(OH)6 microsquares (CIS/ZSOH) heterostructures were devised and fabricated using an easy hydrothermal procedure. The specimens were characterized exhaustively using diverse technologies and used to produce hydrogen. Compared with CdIn2S4 and ZnSn(OH)6, CIS/ZSOH heterostructures presented remarkably superior photocatalytic activities. In addition, CIS/ZSOH-35% exhibited the optimized hydrogen production amount of 4 mmol g−1. Also, the reusable constancy of CIS/ZSOH-35% was very prominent. From relevant characterization results, CIS/ZSOH-35% possessed bigger specific surface area, stronger light-absorption ability and higher charge separation efficiency, which would benefit to improve the photocatalytic performance. Ultimately, the formation of type II heterojunction by CdIn2S4 and ZnSn(OH)6 was confirmed by the band structure and UPS analyses. The study might administer a charming approach to modify the broad band gap photocatalysts.

An S‐scheme AgIn5S8/Bi2MoO6 heterojunction for the photocatalytic degradation of hydrochloride tetracycline

Over the past few decades, the overuse of antibiotics has raised concerns about drinking water and potential health risks, especially the hydrochloride tetracycline (TC‐HCl). Therefore, it is crucial to develop a simple, low‐cost and high‐efficiency photocatalyst for the degradation of the pollutant. A novel photocatalyst with an S‐scheme heterojunction structure of AgIn5S8 and Bi2MoO6 was synthesized by using a solvothermal method. The heterojunction photocatalyst obtained demonstrates superior photocatalytic degradation activity for hydrochloride tetracycline (TC‐HCl) under visible light irradiation. It exhibits higher photocatalytic degradation performance than pure AgIn5S8 and Bi2MoO6 under the same conditions. The heterojunction with 3% AgIn5S8 exhibited the highest degradation efficiency of 63.78% within 40 minutes. Furthermore, the degradation rate is 6.21 times higher than that of AgIn5S8 and 2.18 times higher than that of Bi2MoO6. The improved photocatalytic activity is primarily attributed to the enhanced light absorption and the high rate of carrier separation resulting from S‐scheme heterojunctions.

Synthesis and application of Cu-CaTiO3-GO ternary composite: A new visible-light active multifunctional photocatalyst efficient towards antibiotic cefixime degradation and H2 evolution reaction

To combat the issues of energy scarcity and environmental pollution, a visible-light responsive, ternary photocatalyst (Cu-CaTiO3-GO) was fabricated, by photo-depositing Cu nanoparticles over a CaTiO3-GO binary composite. The physicochemical characteristics of Cu-CaTiO3-GO were investigated using XRD, HR-TEM, FE-SEM, EDS-mapping XPS, Raman, FT-IR, BET, EIS, UV–vis DRS, and PL techniques. In comparison with pristine CaTiO3, and binary composites (Cu-CaTiO3, CaTiO3-GO), the ternary hybrid exhibited superior photocatalytic activity for H2generation as well as antibiotic cefixime (CFX) degradation. Under LED light, the rate of H2 generation over Cu-CaTiO3-GO accumulated to 57.69 mmolh−1, while the photodegradation efficiency for CFX reached 94.1 % in 100 min with 53.4 % of TOC removal. The upgraded performance is credited to synergistic effects of Cu NPs (SPR effect), CaTiO3 (specialized cuboid-like morphology), and GO (high conductivity), co-existing in the trio-hybrid, which resulted in a greatly increased surface area, an expanded spectral response range, a stronger adsorption property, efficient charge migration and separation extent. Ternary catalyst performed well even in the 4 recycling tests (retaining 79.4 % CFX removal and 52.51 mmolh−1 H2 evolution efficiency). In Cu-CaTiO3-GO system, the electron transport channel (Cu → CaTiO3 → GO) with adequate band potentials effectively supports both photocatalytic oxidation and reduction. Photoelectrons are enriched and transferred by plasmonic Cu, and then captured by GO, an e- sink. This maximizes composite photo redox capability, rapidly generating active radicals (OH), and (O2-), degrading CFX to simpler molecules and reducing proton to H2. The effectiveness of Cu-CaTiO3-GO was even tested in the real water matrices. Besides, degradation intermediates of CFX were elucidated using LC-MS, and the decomposition pathway was suggested. Finally, the probable photocatalytic reaction mechanism was deduced for both the degradation and H2 generation processes. The current study proposes a non-noble transition metal-based perovskite-type photocatalytic material for both clean energy generation and wastewater treatment.

Multicolor lignin-derived carbon quantum dots: Controllable synthesis and photocatalytic applications

The cost-effective, high-performance fabrication of multicolor carbon quantum dots (CQDs) from biomass is critical to its prospective application. Lignin, with its phenylpropane structural unit and abundant functional groups, is a reliable precursor for the formation of high-quality CQDs. Here, CQDs from renewable lignin were successfully prepared via a two-step method, and controllable preparation of CQDs to emit blue, green, yellow, and red fluorescence was achieved by adjusting the N-containing acid dopant. The investigated fluorescence mechanism revealed that the energy bandgap of the lignin-derived CQDs decreased and the emission wavelength redshifted as the graphitization degree and number of C=O surface groups increased. The light absorption region of the Bi7O9I3 photocatalysts modified with blue CQDs to red CQDs gradually broadened in the redshifted direction. In particular, compared with pure Bi7O9I3 (70.9%), the red CQDs-modified Bi7O9I3 (RCQD/BOI) can remove 94.7% of antibiotics within 60 min of light irradiation. The superior photocatalytic activity of RCQD/BOI is attributed to the established internal electric field that accelerates charge transfer and effectively separates the photogenerated e+-h+ inside Bi7O9I3. Furthermore, through radical capture, electron paramagnetic resonance (EPR) experiments validated the photocatalytic mechanism of RCQD/BOI and revealed that h+, O2− and OH are key reactants in the photocatalytic degradation process. This promising and sustainable approach for the synthesis of multicolor lignin-derived CQDs opens the avenue of high-value utilization of biomass resources, green production of CQDs nanomaterials, and efficient development of CQDs-based photocatalysts for wastewater treatment.

Graphitic carbon nitride nanosheet and ferroelectric PbTiO3 nanoplates S-scheme heterostructure for enhancing hydrogen production and textile dye degradation

Graphitic carbon nitride (g-C3N4) is a reliable photocatalyst that can be activated by visible light. However, its photocatalytic efficiencies are hindered by the rapid recombination of charge carriers on its surface. A hybrid photocatalyst consisting of a ferroelectric PbTiO3 nanoplate/g-C3N4 S-scheme heterojunction was synthesized using an ultrasonic-assisted hydrothermal method, to overcome the aforementioned limitation. The PbTiO3 nanoplates incorporated into the g-C3N4 matrix created a strong electric field, resulting in superior photocatalytic activities. This improvement can be attributed to the efficient separation of the photogenerated charge carriers. The hybrid photocatalyst (10PTCN) exhibits an impressive H2 evolution rate (1587.82 µmol.g−1.h−1) under simulated solar irradiation. The hybrid photocatalysts demonstrated 99.40 % methylene blue (30 mg·L−1) in 90 min under simulated solar irradiation with remarkable reusability. This work contributes to enhancing the understanding of utilizing ferroelectric 2D nanoplates to develop efficient charge transfer schemes for improved photocatalysts.

2D/2D heterojunction of MgAlTi-LDH/g-C3N4 with oxygen vacancy engineering for enhanced photocatalytic activities under natural sunlight

Semiconductor photocatalysis is an ideal method for wastewater treatment. However, the rapid recombination of photogenerated electron-hole pairs limits the improvement of photocatalytic efficiency. Constructing heterostructures by different energy band-matched semiconductors and surface defect engineering are considered as effective strategies to inhibit the recombination of photogenerated electron-hole pairs. Herein, a novel MgAlTi-LDH/g-C3N4 heterojunction was fabricated by in-situ growth of oxygen vacancy rich MgAlTi-LDH on ultrathin g-C3N4 nanosheets first time for the degradation of methylene blue (MB) under natural sunlight. The optical absorption properties, crystalline phase, microstructure, and morphological analysis of the fabricated materials are subsequently characterized by XRD, FT-IR, UV–vis DRS, TEM, BET and XPS. Owing to Ti-doping, oxygen vacancy rich MgAlTi-LDH exhibited superior photocatalytic activity for MB degradation, which was 5.5 times of that of MgAl-LDH. Furthermore, MgAlTi-LDH/g-C3N4 heterostructures showed a higher photocatalytic activity under visible light irradiation, which was 5.9, 4.9, and 3.2 times of that of MgAl-LDH, MgAlTi-LDH and g-C3N4, respectively. Upon natural sunlight irradiation, MgAlTi-LDH/g-C3N4 can degrade 95 % of MB after 130 min of irradiation. The improvement of photocatalytic activity of MgAlTi-LDH/g-C3N4 was attributed to the synergistic effect of MgAlTi-LDH and g-C3N4, surface oxygen vacancies, and heterostructure interface. This work promotes a new strategy to synthesize high-efficiency photocatalysts for the removal of organic pollutants from wastewater by constructing heterojunctions with surface defects.

Construction of Phosphorus‐Doped g‐C3N4 Nanosheets and Activation of Sodium Percarbonate for Degradation of Organic Pollutants in Wastewater

AbstractA novel phosphorus‐doped graphitic carbon nitride nanosheets (PS‐CN) photocatalyst was prepared by thermal polycondensation and thermal stripping method, and its physicochemical properties were characterized. The results show that PS‐CN formed a thin sheet and multi‐cavity structure by thermal delamination that could enhance the surface area, light reception, and adsorption capacity. The prepared PS‐CN activated sodium percarbonate system (PS‐CN/SPC) was developed for the degradation of dyeing wastewater with methylene blue (MB) as the target pollutant and the degradation mechanism was analyzed. At room temperature (20 °C), the degradation rate of MB in PS‐CN/SPC system within 10 min (88.13 %) was three times that of pure g‐C3N4. In addition, the MB was completely degraded under visible light within 60 min. Moreover, PS‐CN exhibited excellent reusability that the degradation rates of MB have remained above 96 % in five consecutive cycles. The free radical quenching experiments showed that hole (h+), hydroxyl radical (•OH) and superoxide radical (•O2−) all participated in MB degradation, and •OH was the main active species. The PS‐CN/SPC system would provide a high‐value solution for the treatment of dye wastewater due to the low cost of raw materials, superior photocatalytic activity, simple synthesis method, and reusability of the catalyst.

Harnessing In2O3 as an electron aggregator to assist BiOBr nanosheets for enhanced photocatalytic CO2 reduction activity

The advancement of catalysts featuring high carrier separation efficiency enhances photocatalytic reduction performance. This study employed a simple hydrothermal method to anchor In2O3 nanoparticles onto the surface of two-dimensional BiOBr nanosheets, constructing a type-II heterostructure that improves the photocatalytic reduction capability. The composites of 0D/2D In2O3/BiOBr underwent XPS, TPR, and MS characterization, validating the formation of a type-II heterostructure. In2O3 functioned as an electron-aggregating active site that extracted photogenerated electrons from the surface of BiOBr. As a result, the efficiency of charge separation is markedly increased. The results of the CO2 reduction test indicate that In2O3-modified BiOBr exhibits superior photocatalytic activity compared to pure BiOBr, with 2 % In2O3/BiOBr exhibiting the highest reduction performance. The CO yield achieved was 9.81 µmol·g−1·h−1, which is 5.33 times higher than that of pure BiOBr and 42.65 times higher than that of pure In2O3. These findings offer future potential for the application of In2O3 as an electron-accumulating material to enable the photocatalytic reduction of CO2.

A Novel Bismuth‐Rich Bi3O4Cl/BixOyIz Composite with Intensified Photocatalytic Internal Electrical Field for Photocatalytic Degradation of Antibiotics

The enhancement of photocatalytic semiconductor degradation performance through a bismuth‐rich strategy and heterojunction engineering is considered a very effective approach. Herein, the bismuth‐rich Bi3O4Cl/BixOyIz composites are synthesized through a simple solvothermal reaction. The composites have an internal electric field because of their specific layered structure. Due to the difference between their covalent [BixOy]2+ layer and exchangeable halogen ion layer, the enhanced internal electric field facilitates electron transfer at the high‐quality interface of the semiconductor. The trace presence of Bi3O4Cl/BixOyIz (0.1 g L−1) can achieve an 88% removal of tetracycline (20 mg L−1) from the solution phase under visible light illumination in 120 min. The photocatalytic activity is much higher than that of pure BiOCl and BiOI. Furthermore, the material also exhibits high photocatalytic degradation performance for bisphenol A, doxycycline hydrochloride, etc. The excellent results further confirm the application range of the prepared photocatalysts. The superior photocatalytic activity of Bi3O4Cl/BixOyIz is attributed to the formation of a heterojunction and the generation of an internal electric field, which enhances charge separation and oxidation ability. Photoelectrochemical characterization can confirm the above views. Free radical trapping experiments and electron spin resonance show that heterojunctions can produce abundant •O2− and •OH under visible light irradiation.

Built-in electric field intensified by SPR effect to drive charge separation over Ag-AgI/Sb2S3 heterojunction for high-efficiency photocatalytic metronidazole mineralization

The photocatalytic activity of semiconductor is extremely limited due to the rapid recombination of photo-generated carriers and low utilization of solar energy. Herein, a novel Ag-AgI/Sb2S3 (A-S) heterojunction with superior photocatalytic activity was synthesized, in which the optimal Ag-AgI/Sb2S3 heterojunction exhibited 31 times photocatalytic activity of metronidazole removal than that of than that of Sb2S3. The excellent performance of the prepared photocatalysts could be attributed to the synergy of surface plasmon resonance effect by in situ-generated Ag nanoparticles and the built-in electric field of heterostructure, which would broaden the response range of solar light and accelerate the transfer of photogenerated carriers. Besides, characterization and theoretical calculations confirm Ag atoms acquire abundant electrons from Sb atoms of Sb2S3, allowing Ag+ to reduce to Ag0. Meanwhile, a portion of the Ag0 plasma-induced hot electrons reduce O2 to ·O2–, while the remaining portion flows to AgI and circulates in AgI and Ag0 to form a closed loop, thus eliminating the photo-corrosion of AgI. The stability of A-S photocatalyst was also confirmed by five cycle-tests. Furthermore, a reasonable photocatalytic mechanism was proposed by analyzing the intermediates of metronidazole. This work has implications for designing efficient photocatalysts using high-performance materials based on Ag nanoparticles.

Bi, K co-doped graphitic phase carbon nitride for efficient photocatalytic H2O2 production

The emerging photocatalytic production of hydrogen peroxide (H2O2) using graphitic carbon nitride (g-C3N4) has attracted a lot of attention for its potential applications in various fields. However, However, the catalytic activity of pure g-C3N4 is still limited. Herein, Bi, K co-doped g-C3N4 (BixKy-CN) was prepared by co-thermal polymerization of a mixture of potassium nitrate, bismuth nitrate, melamine, and urea. The obtained Bi3.6K3-CN composite possesses more negative conduction and valence band positions that can, to some extent, enhance photocatalytic performance by lowering the energy barrier of redox reactions and by enhancing electron absorption capacity. Additionally, the pyrolysis process of the potassium nitrate and bismuth nitrate has a considerable impact on the formation of the morphology of g-C3N4, generating a porous lamellar-structure with nitrogen defects, resulting in increased oxygen adsorption and utilization capacity. These synergistic effects enable Bi3.6K3-CN to exhibit excellent photocatalytic activity and cycling stability for H2O2 production. After 3 hours of visible light irradiation, the production of H2O2 catalyzed by Bi3.6K3-CN can reach 1207.72 μmol L-1, which is 57 times higher than that of pure g-C3N4.