Efficient Photocatalytic Activity Research Articles

Ag/Bi2WO6 Green Nanocomposites with Highly Efficient Photocatalytic Activity for Dye Degradation and Chromium (VI) Reduction Under Blue LED Irradiation

Ag/Bi2WO6 Green Nanocomposites with Highly Efficient Photocatalytic Activity for Dye Degradation and Chromium (VI) Reduction Under Blue LED Irradiation

Efficient photocatalytic activity over α-MnS/ZIF-67 p-n junction: Revealing the synergistic effects of exposed crystal facets and built-in electric field mechanism

In this investigation, we explored two series of composites comprising p-type α-MnS with selectively exposed {001} or {111} facets, coated with n-type ZIF-67 nanoparticles, to enhance the photocatalytic activity on Rhodamine B (RhB) degradation. The influence of the crystal facet orientation and the p-n junction on the photocatalytic efficacy was also well studied. The α-MnS/ZIF-67 composites displayed enhanced separation of charge carriers and superior light absorption capabilities, benefiting for efficient photocatalysis. The composites with cubic α-MnS morphology exhibited a pronouncedly higher photocatalytic activity relative to those with octahedral α-MnS morphology. The composition of α-MnS with ZIF-67 constructed the formation of a p-n junction with build-in electric field, extending the response into the visible region and promoting the mobility of charge carriers, thereby improving the photocatalytic performance. Our findings revealed that superoxide radicals (O2-) were the major reactive species in the photocatalytic degradation process. This study contributes novel insights into the development of high-performance and stable metal-organic framework (MOF)-based photocatalysts through the crystal facet engineering and the construction of p-n junctions.

Cu2O/H2Ti3O7/Cellulose biohybrid film with efficient photocatalytic and antibacterial activities in solar-driven environmental decontamination

Increasing efforts have been devoted to cellulose-based multifunctional biomaterials for environmental applications. In this study, solvothermal method combined with impregnation reduction process of Cu2+ has been developed to create versatile Cu2O/H2Ti3O7/CP (cellulose paper) biocomposite films that demonstrates efficacy in treating wastewater from organic compounds, disinfecting it from microbes and also purifying the air from volatile organic compounds (VOCs). H2Ti3O7 nanosheets decorated with Cu2O nanoparticles exhibit an excellent visible-light responsibility. Furthermore, the Cu2O/H2Ti3O7/CP biocomposite film demonstrated enhanced efficacy in removing aniline in the liquid phase and 1-propanol in the gaseous phase compared to the H2Ti3O7/CP. This enhanced photocatalytic activity is primarily due to the synergistic effect between Cu2O and H2Ti3O7, which suppresses the recombination of charge carriers and improves their mobility. Reuse tests confirm the stability of the prepared hybrid photocatalyst. Moreover, the biocomposite exhibits good antimicrobial properties, which contributed to the effective inactivation of Escherichia coli. This proves its versatility as a photocatalyst for a broad range of biological and environmental applications.

Boosted photocatalytic degradation performance of TiO2 with enriched oxygen vacancies

In this study, TiO2 with abundant oxygen vacancies (OVs) was prepared through a hydrothermal method in the presence of polyphenylsulphone (PPSU). Introduction of PPSU results in enriched OVs within TiO2 and boosted the level of ∙O2-, dramatically ameliorating photogenerated charges separation efficiency and elevating photocatalytic activity. Compared with the reference TiO2, PPSU-TiO2 exhibits enhance activity in photocatalytic degradation of rhodamine B (RhB) and tetracycline (TC). Analysis reveals that ∙O2- serves as the primary active free radicals in RhB degradation by PPSU-TiO2. Furthermore, PPSU-TiO2 maintains high activity over seven successive cycles, demonstrating excellent stability. Therefore, adding PPSU into the synthesis system of TiO2 is proved to be an effective strategy to enhance photocatalytic performance.

Fabrication of CdIn2S4/ZnS S-scheme heterojunction via in-situ phase transformation for boosting photocatalytic conversion of organic compounds

Developing efficient photocatalysts is one of green and low cost tactic for addressing the environmental deterioration and energy crisis. Therefore, it remains a fantastic and important strategy to design an efficient junction between different semiconductors for harvesting solar light, boosting the redox capability. Herein, the fabrication of ZnS in situ decorated CdIn2S4 (referred to as CIS-Zx) were prepared by converting ZnS particles on Cd2In4S surface by a facile cation exchange method during solvothermal synthesis. According to a series of PEC measurements and DFT calculations, the bending of band edge as well as the establishing of built-in electric field in the interface of CIS/ZnS heterojunction were concluded, causing the formation of in-situ S-scheme heterojunctions in CdIn2S4/ZnS. The in-situ S-scheme heterojunctions can effectively ameliorate the migration behaviors of photo-generated charges. Compared with pure CdInS4, ZnS and physically mixed CdIn2S4/ZnS, the CIS-Zxin-situ S-scheme heterojunction exhibits efficient photocatalytic activity and stability in the selective reduction of aromatic nitro compounds and oxidation of aromatic alcohols, it is hoped that this work will open up a new avenue for innovative applications of in-situ S-scheme heterojunctions.

Green synthesis of silver nanoparticles using Lepidium sativum seed mucilage as a bioreductant/capping agent for efficient antibacterial and photocatalytic activities

Contamination of aquatic resources with organic dyes and pathogenic bacteria ranks among the most serious threats to human survival and the environment. The current work investigated L. sativum seed mucilage as a reducing and capping agent for Ag NPs. From UV–vis spectroscopy, the characteristic surface plasmon resonance peak and the band gap energy of as-fabricated NPs were 440 nm and 2.07 eV, respectively. SEM revealed irregular-shaped NPs with an average diameter of 73.85 nm and EDX disclosed Ag along with C, O, and Si from mucilage’s biomolecules. The antibacterial and antibiofilm results showed higher inhibitory effects against the Gram-positive (B. cereus) than the Gram-negative (E. coli, and E. aerogenes) bacteria. The biosynthesized NPs were impressive in degrading methylene blue (MB, 89.45 %) and methyl orange (MO, 84.78 %) under optimized conditions viz., dye solution (20 ppm), photocatalyst dose (5 mg), light intensity (UV index of 10 +), and irradiation time (120 min). The kinetic data strongly supported the pseudo-first order model with maximum adsorption capacities of 787.40 and 724.64 mg/g for MB and MO, respectively as determined through the Langmuir isotherm model. The photocatalyst exhibited sufficient stability even after six repeated cycles, highlighting its suitability for industrial and commercial applications.

Naphthalene Monoanhydride and Perylene Composites for Efficient Photocatalytic Hydrogen Evolution and Metal-Free Heterogeneous Oxidative Amidation.

This study explores the synthesis of two visible light active organic chromophore-based composites using naphthalene monoanhydride (Np) and 1,7-dibromoperylene monoanhydride diester (PMDE). These chromophores feature favorable optical and electronic properties and polyaromatic skeletons with anhydride functionalities that facilitate π-π interactions between the chromophore and polymeric carbon nitride (CN) or covalent connections of chromophores with NH2 groups of CN. Accordingly, heterogeneous chromophore-CN composite photocatalysts namely, Np/CN(c) and PMDE/CN(c) were prepared by adopting in situ calcination (c) and composites Np/CN(a) and PMDE/CN(a) were prepared by ex situ physical adsorption (a) methods. In situ prepared Np/CN(c) and PMDE/CN(c) composites exhibited H2 evolution rates (HER) of 1069 and 705 μmol h-1 g-1, respectively, which are significantly higher than ex situ Np/CN(a) and PMDE/CN(a) composites with HER of 465 and 252 μmol h-1 g-1, respectively. These rates are 10, 7, 4.8, and 2.5 times higher than the bulk-CN, indicating the potential of these composites for efficient photocatalytic H2 evolution. Surface area normalized HER enhancements were 3.8, 5.3, 6.6, and 4.2 times higher for Np/CN(c), PMDE/CN(c), Np/CN(a), and PMDE/CN(a) respectively compared to bulk-CN. These composite photocatalysts exhibited excellent stabilities under prolonged photoirradiation, with H2 evolution consistently increasing with the light exposure time. Additionally, these metal-free heterogeneous composites demonstrated efficient photocatalytic activities towards oxidative amidation of aromatic aldehydes, with up to 80% product yields, establishing the prospects of combining homogeneous and heterogeneous entities in a metal-free active material in solar energy harvesting.

Spirobifluorene-Based D-A Type Conjugated Polymer Photocatalysts for Water Splitting

Exploring synthetic pathways for efficient photocatalysts has always been a major goal in catalysis. The performance of organic photocatalysts is affected by a variety of complex factors, and how to understand the structure–effect relationship is the key to designing efficient photocatalysts. This work explored the feasibility of constructing large-specific-surface-area conjugated microporous polymers (CMPs) based on stereoscopic units like spirobifluorene and achieving efficient photocatalytic activity by modulating the donor–acceptor (D-A) ratio with dibenzothiophene sulfone. Crosslinked pore structures were successfully constructed, and the specific surface area increased with the ratio of spirobifluorene. When the molar ratio of D-A was 1:20, polymer Spso-3 showed the highest photocatalytic hydrogen production activity, at 22.4 mmol h–1 g–1. The findings indicate that constructing D-A type CMPs should be a promising approach to improving the performance of photocatalytic water separation. The appropriate push–pull effect of the D-A structure promotes the photo-induced separation of electron–hole pairs, and the porous structure built on steric units offers ample space for catalytic reactions. This work could provide case references for structural design and the structure–effect relationship of efficient polymer photocatalysts.

Room-Temperature Single-Phase Synthesis of Semiconducting Metal-Covalent Organic Frameworks With Microenvironment-Tuned Photocatalytic Efficiency.

In order to improve the solubility of metallated monomers and product crystallinity, metal-covalent organic frameworks (MCOFs) are commonly prepared via high-temperature sol-vothermal synthesis. However, it hampers the direct extraction of crystallization evolution information. Exploring facile room-temperature strategies for both synthesizing MCOFs and exploiting the crystallinity mechanism is extremely desired. Herein, by a novel single-phase synthetic strategy, three MCOFs with different microstructure is rapidly prepared based on the Schiff base reaction between planarity-tunable C3v monomers and metallated monomers at room temperature. Based on detailed time-dependent experiments and theoretical calculations, it is found that there is a planarity-tuned and competitive growth relationship between disordered structures and crystal nucleus for the first time. The high planarity of monomers boosts the formation of crystal nucleus and rapid growth, suppressing the forming of amorphous structures. In addition, the microenvironment effect on selective photocatalytic coupling of benzylamine (BA) is investigated. The strong donor-acceptor (D-A) MCOF exhibits efficient photocatalytic activity with a high conversion rate of 99% and high selectivity of 99% in 5h under the 520nm light irradiation. This work opens a new pathway to scalable and efficient synthesis of highly crystalline MCOFs.

Fabrication of CoTiO3/MgIn2S4 S–scheme heterojunctions with efficient charge separation to enhance the photocatalytic activities of hydrogen generation and formaldehyde removal

The efficient separation of photoinduced charge carriers is a primary factor in the catalytic performance of photocatalysts. Constructing S-scheme heterojunctions is a prospective strategy to efficiently and spatially separate photoinduced charges while retaining strong oxidation and reduction capacities of the catalyst system. Herein, CoTiO3/MgIn2S4 (abbreviated x% CTO/MIS, where x% represents the mass ratio of CTO-to-MIS; x = 5, 10, 15, 20, and 25) heterojunctions were successfully synthesized using a hydrothermal method. These heterojunctions exhibited highly efficient and reusable visible-light photocatalytic properties for hydrogen (H2) generation and formaldehyde (HCHO) degradation. Notably, the 15 % CTO/MIS demonstrated an admirable H2 evolution activity of 631.77 μmol·g−1·h−1, with AQE = 2.25 % at λ = 420 nm, and an HCHO degradation rate of 67.18 %. The intermediate products generated during HCHO removal were identified applying in situ diffuse reflectance infrared Fourier transform spectroscopy. The exceptional catalytic performance of the synthesized materials was attributed to the boosted light absorption and utilization, rapidly separation, and transfer of photoproduced charge carriers, which resulted from the internal electric field of the S-scheme mechanism. Moreover, the S-scheme electron transfer pathway for the CTO/MIS catalyst system during the photocatalytic process was confirmed using electron spin resonance spectroscopy, free-radical capturing tests, density functional theory calculations, in situ X-ray photoelectron spectroscopy, and semiconductor energy band theory. The study offers an innovative perspective for establishing S-scheme heterojunctions with highly efficient and stable photocatalytic activity for H2 generation and HCHO removal.

Construction of Ba-doped Ag3PO4/SnO2 type-II nanocomposites as a promising photocatalyst for boosting photocatalytic degradation of BY28 dye and redox conversion of Cr(VI)/Cr(III)

In the present study, Ba-doped Ag3PO4/SnO2 type-II heterojunction nanocomposites were fabricated and systemically investigated for the degradation of basic yellow 28 (BY28) dye and Cr(VI) reduction in the photocatalytic process under visible-light irradiation. XRD, XPS, FESEM, DRS, and PL analyses were performed to determine the characterization of synthesized photocatalysts. The optimal 1.5 wt% Ba-doped Ag3PO4/SnO2 nanocomposite exhibited an efficient photocatalytic activity with rate constant of 0.0491 min−1 for BY28 degradation and 0.0261 min−1 for Cr(VI) reduction, which is 13.3 and 7.5 times higher than that of the SnO2 nanorods. Such enhanced performance can arise from the one-dimensional structure, extended light absorption toward the visible region, formation of the type II heterojunction, the new defect-related energy states, and efficient charge separation. Furthermore, the photostability of the photocatalysts was studied and a plausible photocatalytic mechanism was proposed.

Lignocellulosic materials extraction from waste baby diaper to prepare light-responsive metal oxide/carbon composite for efficient organic dye pollutant removal

The bimetal oxide comprising nickel incorporated β-Bi2O3 on graphitic carbon in the form of bismuth nickel oxide (BNO@C) was prepared by waste lignocellulosic materials collected from cheap and readily available baby diapers. The prepared BNO@C was used to photocatalytically degrade methylene blue under UV-light irradiation. Prior to the photocatalytic performance analysis, the formation of BNO@C was confirmed by various morphological and structural analysis including SEM, TEM, XRD, and XPS analyses. As a result, the two-dimensional nanosheet morphology and tetragonal primitive lattice-structure with 2+ and 3+ oxidation stated Ni and Bi in BNO@C structural formulation were confirmed. In photocatalysis experimentation examined with BNO@C, the maximum methylene blue removal percentage of 96.7 % was achieved within 16 min. The influence of Ni2+ in BNO@C was identified by performing the photocatalytic performance of bare NiO@C and Bi2O3@C, yielding maximum dye removal of 32.8 % and 64.5 %, respectively. The efficacy of Ni in BNO@C toward increasing catalytic efficiency was identified using DFT analysis, revealing the acting of Ni as active sites for improved light absorption tendency. These findings show a novel strategy to prepare a low-cost BNO@C catalyst with efficient photocatalytic activity, opening a new path for a cost-efficient wastewater treatment approach.

Exploring the diverse applications of sol–gel synthesized CaO:MgAl2O4 nanocomposite: morphological, photocatalytic, and electrochemical perspectives

A nanocomposite of CaO:MgAl2O4 was synthesized through a straightforward and cost-effective sol–gel method. The investigation of the novel CaO:MgAl2O4 nanocomposite encompassed an examination of its morphological and structural alterations, as well as an exploration of its photocatalytic activities and electrochemical characteristics. XRD analysis revealed a nanocomposite size of 24.15 nm. The band gap, determined through UV studies, was found to be 3.83 eV, and scanning electron microscopy (SEM) illustrated flake-like morphological changes in the CaO:MgAl2O4 samples. TEM, HRTEM, and SAED studies of a CaO:MgAl2O4 nanocomposite would reveal important details about its morphology, crystallography, and nanostructure. Photocatalytic activity was quantified by studying the degradation of Acid Red-88 (AR-88) dye in a deionized solution, achieving a 70% dye degradation under UV irradiation in 120 min. Plant growth examinations were carried out using dye degraded water to test its suitability for agriculture. The electrochemical energy storage and sensing applications of the prepared nanocomposite were examined using CaO:MgAl2O4 modified carbon paste electrode through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In conclusion, the synthesized CaO:MgAl2O4 nanocomposite demonstrated promising morphological and structural characteristics, efficient photocatalytic activity, and potential applications in electrochemical energy storage, highlighting its versatility for various technological and environmental applications.Graphical abstract

Impact of Imine Bond Orientations and Acceptor Groups on Photocatalytic Hydrogen Generation of Donor-Acceptor Covalent Organic Frameworks.

Covalent organic frameworks (COFs) have emerged as one of the most studied photocatalysts owing to their adjustable structure and bandgaps. However, there is limited research on regulating the light-harvesting capabilities of acceptor building blocks in donor-acceptor (D-A) isomer COFs with different bond orientations. This investigation is crucial for elucidating the structure-property-performance relationship of COF photocatalysts. Herein, a series of D-A isostructural COFs are synthesized with different imine bond orientations using benzothiadiazole and its derivatives-based organic building units. Extended light absorption is achieved in COFs with acceptor groups that have strong electron-withdrawing capacities, although this resulted a decreased hydrogen generation efficiency. Photocatalytic experiments indicated that dialdehyde benzothiadiazole-based COFs, HIAM-0015, exhibit the highest hydrogen generation rate (17.99mmol g-1 h-1), which is 15 times higher than its isomer. The excellent photocatalytic performance of HIAM-0015 can be attributed to its fast charge separation and migration. This work provides insights into the rational design and synthesis of D-A COFs to achieve efficient photocatalytic activity.

Modulating Surface-Adsorbed Oxygen Species of Bismuth Silicate by a Solid Solution Strategy for Efficient Adsorption and Photocatalytic Activity.

Bismuth silicate photocatalysts suffer from insufficient photocatalytic activity due to an insufficient number of surface active sites and low carrier separation and transport efficiency, which can be solved by defect modulation. Herein, Bi12SiO20/Bi2O2SiO3-BiOClxBr1-x (BSOCB) photocatalysts with a high concentration of surface-adsorbed oxygen species (SAOS) are synthesized by introducing a BiOClxBr1-x solid solution to modify nonhomogeneous BSO via an ion exchange strategy. The introduction of a solid solution enables the generation of dispersed nanoflowers and the regulation of SAOS due to the fact that anion-cation copolymerization guides the crystal growth, and the defects generated by the lattice distortion modulate the concentration of SAOS on the catalysts during the solid solution process. The obtained typical BSOCB photocatalyst possesses both high adsorption and photocatalytic properties, and the results show that it not only can almost completely degrade the traditional pollutant RhB within 20 min but also strongly degrades antibiotics, such as CIP (light for 150 min, 96%), NFX (light for 150 min, 87%), and TC (light for 150 min, 77%). This work provides a new approach for obtaining bismuth-based photocatalysts with controllable morphology and a large number of surface active sites and provides a theoretical and experimental basis for expanding the application scenarios of photocatalysts.

MoC nanoparticles embedded in superior thin g-C3N4 nanosheets for efficient photocatalytic activity

Photogenerated charge carrier transfer efficiency in graphitic carbon nitride (g-C3N4) based heterostructures depended strongly on the interface nature. In this paper, MoC nanoparticles less than 5 nm were implanted in superior thin g-C3N4 nanosheets to create high charge carrier separation and transfer efficiency. Cubic MoC in N-doped graphitic carbon was first fabricated using dicyandiamide and ammonium molybdate tetrahydrate at 800 °C. The MoC nanoparticles were homogeneously implanted in g-C3N4 nanosheets by further thermal polymerization of bulk g-C3N4 prepared using melamine and MoC/C composites to create a Schottky junction which was confirmed by band gap analysis and free radical capture test. Melamine and dicyandiamide also play important role to create highly efficient catalysts. The MoC nanoparticles revealed fine crystallinity. A well-developed interface between MoC and g-C3N4 was observed. Because of high conductivity of MoC, well-developed interface, and co-catalyst role of MoC, the MoC/g-C3N4 junction exhibited ideal photocatalytic activity for dye degradation and water splitting. The kinetic constant rate of Rhodamine B degradation using a MoC/g-C3N4 sample created by optimized conditions was 0.061 min−1 which was 8.7 times of that of pristine g-C3N4 nanosheets. In the case of without co-catalyst addition, the photocatalytic hydrogen generation rate using this composite sample was 233.0 μmol g−1 h−1 which was 15.2 times of that of initial g-C3N4 nanosheets. These results supply an efficient approach for the first time to homogeneously distribute small cubic MoC nanoparticles in superior thin g-C3N4 nanosheets to construct heterostructures and greatly reduce photogenerated charge carrier recombination.

Clinacanthus nutans crude polysaccharide extract as a green platform for microwave-assisted synthesis of silver nanoparticles: Optimization, characterization, and evaluation of bioactivities

Clinacanthus nutans (C. nutans) is a plant in tropical Asia with proven biological activities. The optimized extraction method of C. nutans crude polysaccharide (CNP) uses water in the presence of an ultrasound-assisted mechanical method (UL_CNP). However, the use of UL_CNP for the synthesis and optimization of silver nanoparticles (AgNP), particularly their anticancer and photocatalytic properties, remains unexplored. Hence, this research aimed to employ a green method using UL_CNP and silver nitrate to produce AgNP (UL_AgNP) with a small size and assess its potential toxicity, anticancer, and photocatalytic activities. The synthesis condition was optimized using the Box–Behnken design method. The synthesized UL_AgNP showed the surface plasmon resonance peak at 458 nm. The optimized synthesis condition produced spherically shaped UL_AgNP with a size of 5.21 ± 1.92 nm and a zeta potential of −26.33 ± 0.93 mV. An X-ray diffraction analysis exhibited intense Bragg's reflection peaks at (111), (200), (220), and (311), having a face-centered cubic structure of AgNP. Attenuated total reflectance-Fourier-transform infrared spectroscopy and energy-dispersive X-ray spectroscopy further confirmed the presence of silver in the synthesized UL_AgNP. The brine shrimp lethality test of UL_AgNP reported a lethal concentration 50 value of <7.8 μg/mL after 24 h. The UL_AgNP exhibited antiproliferative activity against MCF-7 cells with a half-maximal inhibitory concentration value of 4.96 ± 0.31 μg/mL by inducing S-phase cell cycle arrest, apoptotic effect, and reduction of cell migration. Furthermore, UL_AgNP proved its efficient photocatalytic activity against methylene blue dye (50.22 % ± 0.06 %, after 10 min at a concentration of 50 μg/mL). Therefore, the UL_AgNP exhibited promising antiproliferative activity against MCF-7 cells, highlighting their potential as a therapeutic agent. Further investigations are needed to elucidate the precise mechanism of their action.

Platinum nanoparticles decorated TiO2 nanotubes for VOCs and bacteria removal in simulated real condition: Effect of the deposition method on the photocatalytic degradation process efficiency

The incorporation of noble metals onto TiO2 nanostructure is considered as a promoting method to enhance the photocatalytic degradation of pollutant in air treatment process. In this study, highly organized TiO2 nanotubes (NTs) were grown by the anodization method of Titanium substrates. The TiO2-NTs were successfully decorated by platinum (Pt) nanoparticles (NPs) using two different deposition methods: (1) electrodeposition and (2) photodeposition.We explore the impact of different deposition methods on the morphology of Pt nanoparticles (NPs) dispersed onto TiO2 nanotubes and the optical characteristics of Pt-TiO2 nanocomposites, investigating their efficacy in photocatalytic degradation We investigate the effect of varying the deposition method on the morphology of Pt-NPs dispersed onto TiO2 nanotubes and the optical properties of the Pt-TiO2 nanocomposites and their efficient photocatalytic activity degradation against Volatile Organic Compounds (VOCs) and bacteria. Scanning and Transmission Electron Microscopy (SEM and TEM) reveal a nanotubular TiO2 anatase structure adorned with Pt NPs, with the quantity and size of NPs contingent upon the deposition technique employed. The photoluminescence (PL) spectra demonstrate that the Pt/TiO2 heterojunction facilitates the separation of photogenerated charges, thereby diminishing carrier recombination rates. To point out the effect of Pt NPS, both pure TiO2 and Pt/TiO2 heterojunction were tested in the photodegradation of Ethyl Acetate (EA). The Pt/TiO2 heterojunction exhibits superior photocatalytic performance compared to TiO2 in EA degradation, regardless of the Pt deposition method employed. Optimal results are achieved with 120 s of Pt electrodeposition and 3 h of Pt photodeposition under visible irradiation, yielding kinetic constants of approximately 0.245 and 0.195 mg.m−3.s−1, respectively, underscoring the pivotal role of the platinum deposition method in pollutant photodegradation. Respectively simultaneous removal of EA and bacteria (Escherichia coli) was tested using Pt and non-Pt decorated TiO2 NTs. We attributed a total degradation of the bacteria after 180 min using the two efficient photocatalysts Electro 120 s and Photo 3 h compared to 60 % of degradation using pure TiO2 nanotubes.

Composition-Regulated Photocatalytic Activity of ZnIn2S4@CdS Hybrids for Efficient Dye Degradation and H2O2 Evolution.

Heterostructures of visible light-absorbing semiconductors were prepared through the growth of ZnIn2S4 crystallites in the presence of CdS nanostructures. A variety of hybrid compositions was synthesized. Both reference samples and heterostructured materials were characterized in detail, regarding their morphology, crystalline character, chemical speciation, as well as vibrational properties. The abovementioned physicochemical characterization suggested the absence of doping phenomena, such as the integration of either zinc or indium ions into the CdS lattice. At specific compositions, the growth of the amorphous ZnIn2S4 component was observed through both XRD and Raman analysis. The development of heterojunctions was found to be composition-dependent, as indicated by the simultaneous recording of the Raman profiles of both semiconductors. The optical band gaps of the hybrids range at values between the corresponding band gaps of reference semiconductors. The photocatalytic activity was assessed in both organic dye degradation and hydrogen peroxide evolution. It was observed that the hybrids demonstrating efficient photocatalytic activity in dye degradation were rather poor photocatalysts for hydrogen peroxide evolution. Specifically, the hybrids enriched in the CdS component were shown to act efficiently for hydrogen peroxide evolution, whereas ZnIn2S4-enriched hybrids demonstrated high potential to photodegrade an azo-type organic dye. Furthermore, scavenging experiments suggested the involvement of singlet oxygen in the mechanistic path for dye degradation.

(Invited) Controlled Synthesis of Cocatalyst-Semiconductor Hybrid Nanomaterials for Photocatalytic Water Splitting

With the escalating global demand for energy, mitigating anthropogenic climate change necessitates the pursuit of carbon-neutral energy sources to diminish reliance on fossil fuels. Utilizing particulate photocatalysts for solar-light-driven water splitting presents a promising and sustainable paradigm for the large-scale production of storable and clean H2 fuel. To improve the solar energy conversion efficiency, coupling the photocatalysts with cocatalysts is a broadly adopted approach not only to facilitate charge separation and transport but also to serve as reaction sites and accelerate water-splitting reactions. Recent breakthroughs in colloidal synthesis enable the fabrication of advanced nanoparticles with precise control over size and composition. Colloidal NPs represent ideal cocatalyst candidates due to their capacity to provide numerous active sites and facilitate uninterrupted light absorption by the semiconductor. Here, we introduce our approach to synthesize cocatalyst-semiconductor hybrids as efficient photocatalysts, including the alloying of platinum group metal nanoparticle cocatalysts and the control of single-atom cocatalyst locations on semiconductor nanoparticles.Platinum group metals exhibit high efficiency as cocatalysts in the hydrogen evolution reaction, attributed to their favorable catalytic and electronic properties. Bimetallic alloy systems, in general, can considerably modulate their electronic structures, resulting in exceptional physicochemical properties surpassing those of their monometallic counterparts. Herein, we synthesized PtRu solid-solution alloy nanoparticles as high-performance H2 evolution reaction cocatalysts. The rational integration of PtRu nanoparticles with Al-doped SrTiO3 photocatalyst through liquid-phase adsorption and successive two-step annealing ensure the uniform deposition of PtRu alloy nanoparticles with a solid-solution structure. The bimetallic synergy between Pt and Ru induces higher electrocatalytic activity for the hydrogen evolution reaction and a superior electron-capturing property than its Pt counterpart. Modification of Al-doped SrTiO3 with PtRu alloy nanoparticles, CrOx, and CoOOH results in efficient photocatalytic overall water-splitting activity with an apparent quantum yield of 65% at 365 nm. This work introduces a framework to elucidate catalytic trends, offering rational design guidance for the development of bimetallic solid-solution nanoparticles as highly active cocatalysts for overall water splitting.Single-atom cocatalysts dispersed on semiconductor materials exhibit outstanding heterogeneous catalytic properties through the interactions between the single atoms and the photocatalyst. The nature of these interactions depends on whether the single atoms are located on the surface or within the interior of the photocatalyst. In this work, the location-selective placement of single atoms is achieved by carefully adjusting experimental procedure. Using CdSe nanoplatelets as a support, applying different Pt precursor complexes, solvent, and workup process resulted in location selective deposition of Pt atoms outside/inside CdSe nanoplatelet support. In photocatalytic hydrogen evolution reaction, the surface-adsorbed single Pt atoms exhibit higher stability than the substituted ones. This study provides a viable strategy for the structurally precise synthesis and design of single-atom catalysts.