Preparation Of Photocatalysts Research Articles

Use of Natural Zeolite Clinoptilolite in the Preparation of Photocatalysts and Its Role in Photocatalytic Activity

The use of natural zeolite clinoptilolite in preparing photocatalysts and its function in photocatalysis are discussed in this review. The importance of advanced oxidation processes (AOPs) and the potential of heterogeneous photocatalysis in removing environmental pollutants are emphasized. The review focuses on the synergistic effects of clinoptilolite with semiconductors (TiO2, ZnO, CuO, SnO2, and NiO) to prepare stable and active photocatalysts, highlighting recent advancements in this field. It explores clinoptilolite’s structural characteristics, highlighting its microporous nature, adaptable framework, and improved textural properties due to acid and alkali treatments. Particle size, crystal phase, and calcination temperature are three key synthesis parameters that affect photocatalytic activity and are highlighted in the discussion of these parameters and their methods. A discussion is held regarding the processes and mechanisms of photocatalytic degradation of different organic compounds under varying irradiation conditions, including UV, visible, and ambient sunlight. Clinoptilolite is vital in improving supported semiconductor oxides’ photocatalytic efficiencies, which aid in pollutant degradation and environmental remediation.

Preparation of TiO2 composite photocatalyst using amorphous SiO2 microspheres loaded with spent SCR catalysts

The products of S-SCR grinding and alkali treatment (S-SCR-T, primarily consisting of anatase TiO2 with a size less than 20 nm) were utilized as photocatalysts, while SiO2 microspheres (MS-SiO2) were used as carriers. A TiO2 composite photocatalyst (M-Si/SR-Ti) was prepared by wet mechanical grinding. The results demonstrate that in M-Si/SR-Ti, S-SCR-T was uniformly loaded on the MS-SiO2 surface in a well-dispersed state and firmly bonded at the interface with Si–O–Ti bonds. M-Si/SR-Ti prepared under optimized conditions exhibited excellent photocatalytic degradation and recycling properties for methyl orange. The degradation rate of methyl orange solution at 10 ppm for 60 min under UV irradiation was 97%, which was comparable to that of S-SCR-T, and remained unchanged after four cycles of recycling. Compared with S-SCR-T, M-Si/SR-Ti exhibited significantly improved settlement recovery performance in water. The loading of S-SCR-T on the MS-SiO2 surface, which increased the exposure of the nano-TiO2 active site and decreased the energy gap, was the mechanism responsible for improving the photocatalytic performance of M-Si/SR-Ti. This study positively impacted the effort to efficiently utilize and increase the value of S-SCR and reduce the cost of the photocatalyst.

Efficient photocatalytic hydrogen production of Ni-Co layered double hydroxides (Ni-Co LDHs) anchored with reduced graphene oxide (rGO) hybrid composite

Using a suitable co-catalyst to boost photocatalytic H2 evolution from water splitting is crucial. Herein, we designed pristine NiCo-LDH and reduced graphene-oxide supported nickel-cobalt layered double hydroxide nanosheets (NiCo-LDH/rGO) as photocatalyst for the first time to evaluate the hydrogen production performance. Adding graphene has the potential to significantly increase electrical conductivity, and the supported NiCo-LDH has the potential to significantly reduce the likelihood of graphene self-aggregation. The effectiveness of its photocatalytic hydrogen generation was analyzed using a set of characterizations. The H2 evolution rates for pure rGO were 345.2 μmolh-1g-1, whereas those for Ni-Co LDH/rGO were 578.2 μmolh-1g-1. Average hydrogen generation per hour for the Ni-Co LDH/rGO composite material was 2032.1 μmolh-1g-1, which was 5.8 and 3.5 times that of rGO and Ni-Co LDH/rGO, respectively, NiCo-LDH@rGO's synergistic impact on the NiCo-LDH boosts the H2 generation pathway by increasing the catalyst's stability as well as performance by exposing active sites and speeding up electron transport. The produced nanocomposite shows excellent spatial charge separation and quicker electron transport across the conductive network of rGO, as shown by the photocurrent response test and photoluminescence (PL) spectra. The results of this study provide a fresh perspective on the practical use and synthesis of the inexpensive and effective NiCo-LDH/rGO, demonstrating the standard deviation of logical planning and preparation of high-performance photocatalysts.

Accelerated sonochemical fabrication of MIn2S4 (M = Zn, Mg, Ni, Co) for ultra-high photocatalytic hydrogen peroxide production

Ternary metal sulfide (MIn2S4) by virtue of large extinction coefficient, suitable band gap and stability, has been proposed as a candidate for photocatalytic synthesis hydrogen peroxide (H2O2). However, MIn2S4 is conventionally synthesized by solvothermal method that is generally characterized by tedious operational steps and long reaction time. In this work, four sonoMIn2S4 (M = Zn, Mg, Ni, Co) were successfully prepared by sonochemical method within 2 h. These as-synthesized sonoMIn2S4 delivered much high-efficient photocatalytic H2O2 generation. Particularly, the sonoZnIn2S4 presented a H2O2 production rate of 21295.5 μmol∙g−1∙h−1 in water/benzylalcohol system, which is 3.0 times that ZnIn2S4 prepared by solvothermal method. The remarkably improved photocatalytic performance of sonoZnIn2S4 might be due to the multiple defects and fast electron-hole pair separation caused by ultrasound cavitation effect. Other metal sulfide photocatalysts with high performance were efficiently fabricated by facile sonochemical technology as well. The sonochemical method realized the rapid preparation of metal sulfide photocatalysts and efficient production of H2O2, which benefits to meet the United Nations Sustainable Development Goals (SDGs) including SDG-7 and SDG-12.

Resource utilization of MSWI fly ash supporting TiO2/BiOCl nanocomposite for enhanced photocatalytic degradation of sodium isopropyl xanthate: Mechanism and performance evaluation

The removal of organic pollutants in water environments and the resource utilization of solid waste are two pressing issues around the world. Facing the increasing pollution induced by discharge of mining effluents containing sodium isopropyl xanthate (SIPX), in this work, municipal solid waste incineration fly ash (MSWI FA) was pretreated by hydrothermal method to produce stabilized FA, which was then innovatively used as support for the construction of FA/TiO2/BiOCl nanocomposite (FTB) with promoted photocatalytic activity under visible light and natural sunlight. When the content of FA was 20 wt% and the mass ratio of TiO2 to BiOCl was 4:6, a remarkable performance for the optimal FTB (20-FTB-2) was achieved. Characterizations demonstrated that TiO2 and BiOCl uniformly dispersed on FA contributing to high surface area and broad light adsorption of FTB, which exhibits excellent adsorption capacity and light response ability. Build in electric field formed in the interface of TiO2/BiOCl heterojunction revealed by density functional theory calculations accelerated the separation of photoinduced e− and h+, leading to high efficiency for SIPX degradation. The synergetic effect combined with adsorption and photocatalytic degradation endowed 20-FTB-2 superior SIPX removal efficiency over 99% within 30 min under visible light and natural sunlight irradiation. The photocatalytic degradation pathways of SIPX were determined through theoretical calculations and characterizations, and the toxic byproduct CS2 was effectively eliminated through oxidation of •O2−. For 20-FTB-2, reusability of photocatalyst was showed by cycle tests, also the concentrations of main heavy metals (Pb, Zn, Cu, Cr, and Cd) in the liquid phases released during photocatalyst preparation process (< 1 mg/L) and photodegradation process (< 8.5 μg/L) proved the satisfactory stability with low toxicity. This work proposed a novel strategy to develop efficient and stable support-based photocatalysts by utilizing MSWI FA and realize its resource utilization.

Theoretical Study of p-Block Metal Single-Atom-Loaded Carbon Nitride Catalyst for Photocatalytic Water Splitting.

Graphitic carbon nitride (g-C3N4), recognized for its considerable potential as a heterogeneous photocatalyst in water splitting, has attracted extensive research interest. By using density functional theory (DFT) calculations, the regulatory role of p-block metal (PM) single atoms on the photocatalytic activity of g-C3N4 in overall water splitting was systematically explored. The incorporation of PM atoms (Ge, Sn and Pb) led to a reduction in the overpotentials required for both the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER). Combined with the electronic structures analysis via hybrid functional, it was found that the introduction of Ge, Sn or Pb optimizes the positions of the valence band maximum (VBM) and the conduction band minimum (CBM), providing a robust driving force for HER and ensuring substantial driving force for OER. Meanwhile, the presence of these three PMs induces the spatial separation of VBM and CBM, inhibiting the recombination of carriers. These findings have significant implications for the design and preparation of efficient photocatalysts.

Insights into bimetallic single-atom-doped g-C3N4 photo-catalysts for CO2 conversion to HCOOH: A DFT study

Developing low-cost, high-efficiency non-noble metallic photocatalytic materials is crucial for CO2 reduction. This paper investigates the substitution of noble metals dopant to a bimetallic non-noble Fe/Co dopant for g-C3N4 to enhance the photocatalytic CO2 reduction performance via density functional theory (DFT) calculations. This study examines the structure, electronic properties, CO2 adsorption configurations, and the transition states and Gibbs free energy of CO2 reduction to HCOOH on noble metal Pt/g-C3N4 doped, single-atom Fe/g-C3N4 doped, and bimetallic Fe/Co doped g-C3N4 catalysts, revealing the mechanisms of catalyst-mediated CO2 reduction. The results demonstrate that the introduction of Fe/Co bimetallic atoms leads to more efficient charge transfer, attributed to the synergistic and electronic effects of the bimetallic coupling, with a charge of 1.264, which is 2.2 and 1.2 times greater than that of Pt and Fe doped g-C3N4, respectively. Furthermore, the stronger adsorption energy of CO2 molecules on Fe/Co/g-C3N4 compared to pure g-C3N4, Pt/g-C3N4, and Fe/g-C3N4 indicates that adsorption on Fe/Co/g-C3N4 is more conducive to CO2 activation. The CO2 reduction reaction (CO2RR) calculations reveal that Fe/Co/g-C3N4 exhibits a lower reaction barrier of 0.789 eV compared to noble metal-doped Pt and single-atom Fe, due to the reduction of the reaction mechanism's energy barrier by the Fe/Co bimetallic doped g-C3N4, which facilitates a more effective reduction of CO2 to HCOOH. As a result, Fe/Co/g-C3N4 emerges as an effective alternative to noble metal-based photocatalysts. This study provides theoretical guidance for the preparation of efficient non-noble metal photocatalysts.

A Wooden Carbon-Based Photocatalyst for Water Treatment.

Due to a large number of harmful chemicals flowing into the water source in production and life, the water quality deteriorates, and the use value of water is reduced or lost. Biochar has a strong physical adsorption effect, but it can only separate pollutants from water and cannot eliminate pollutants fundamentally. Photocatalytic degradation technology using photocatalysts uses chemical methods to degrade or mineralize organic pollutants, but it is difficult to recover and reuse. Woody biomass has the advantages of huge reserves, convenient access and a low price. Processing woody biomass into biochar and then combining it with photocatalysts has played a complementary role. In this paper, the shortcomings of a photocatalyst and biochar in water treatment are introduced, respectively, and the advantages of a woody biochar-based photocatalyst made by combining them are summarized. The preparation and assembly methods of the woody biochar-based photocatalyst starting from the preparation of biochar are listed, and the water treatment efficiency of the woody biochar-based photocatalyst using different photocatalysts is listed. Finally, the future development of the woody biochar-based photocatalyst is summarized and prospected.

TiO2 nanorod decorated with MoS2 nanospheres: An efficient dual-functional photocatalyst for antibiotic degradation and hydrogen production

The design and preparation of dual-functional photocatalysts for simultaneously realizing photocatalytic wastewater purification and hydrogen energy generation pose significant challenges. This article presents the engineering of a binary heterostructured photocatalyst by combining TiO2 (nanorods) and MoS2 nanosphere using a straightforward solvothermal method and the assessment of the phase structures, morphologies, and optical properties of the resulting nanocomposites using diverse analytical techniques. The TiO2(Rod)/MoS2 composite exhibits remarkable efficacy in degrading ciprofloxacin, achieving 93% removal rate within 1 h, which is four times higher than that of bare TiO2. Moreover, the optimized TiO2(Rod)/MoS2 presents an outstanding hydrogen production rate of 7415 μmol g−1, which is ∼24 times higher than that of pristine TiO2. Under UV–visible light irradiation, the TiO2(Rod)/MoS2 heterojunction displays an exceptional photocatalytic performance in terms of both photodegradation and hydrogen production, surpassing the performance of TiO2 particle/MoS2. The study findings demonstrate that TiO2(Rod)/MoS2 nanocomposites exhibit considerably improved photocatalytic degradation and hydrogen generation activities. Based on the experimental results, a possible mechanism is proposed for the transfer and separation of charge carriers in Z-scheme heterojunctions.

A novel nano-cerium oxide functionalized biochar composite for degradation of organic dye: insight of the photocatalysis mechanism.

Recently, visible-light-driven photocatalysis attracts much concerns in the remediation of environmental organic pollutants. In this study, the cerium doped biochar was fabricated through the hydrothermal method, and served as an efficient photocatalyst towards rhodamine B degradation under visible light irradiation. Almost 100% of rhodamine B was removed by 2.0g·L-1 cerium doped biochar after 60min of visible light irradiation at pH 3, but only about 25.50% and 29.60% of rhodamine B was removed by cerium dioxide and biochar under identical conditions. The degradation process coincided well with the pseudo-first-order kinetic model, and the photodegradation rate constant of cerium doped biochar was 0.0485·min-1, which was respectively 97 and 44 times that of biochar (0.0005·min-1) and cerium dioxide (0.0011·min-1). According to the trapping experiments and electron spin resonance spectroscopy analysis, h+, O2-∙ and ∙OH all participated in the degradation of rhodamine B in the cerium doped biochar photocatalytic systems, and the function of h+ and ∙OH was dominated. Consequently, the biochar could not only be an excellent carrier for supporting cerium dioxide, but also greatly improved its photocatalytic activity. The band gap of cerium doped biochar was narrower than cerium dioxide, which could improve the separation and migration of photogenerated electron-hole pairs under visible-light excitation, thus ultimately enhanced the degradation of rhodamine B. This work provided a deeper understanding of the preparation of biochar-based photocatalyst and its application in the remediation of environmental organic pollution.

Enhanced visible light photocatalytic performance of carbon and oxygen co-doped carbon nitride with a three-dimensional structure: Performance and mechanism study

As a cost-effective photocatalyst, carbon nitride (g-C3N4) holds tremendous promise for addressing energy shortages and environmental pollution. However, its application is limited by disadvantages such as low specific surface area and easy recombination of photogenerated electron-hole pairs. This study introduces C and O co-doped g-C3N4 with a three-dimensional (3D) structure achieved through a straightforward one-step calcination process, demonstrating excellent photocatalytic activity of hydrogen production and oxytetracycline degradation, with superoxide radicals as the primary active species. We propose a plausible enhanced mechanism based on systematic characterizations and density functional theory calculations. The 3D structure confers a substantial specific surface area, enhancing both the adsorption area and active sites of catalysts while bolstering structural stability. Co-doping optimizes the band structure and electric conductivity of the catalyst, facilitating rapid migration of photogenerated charges. The synergistic effects of these enhancements significantly elevate the photocatalytic performance. This study presents a convenient and feasible method for the preparation of dual-regulated photocatalysts with outstanding performance.

Enhanced hydrogen evolution and tetracycline degradation by a Z-scheme g-C3N4 nanosheets loaded CeO2 photocatalyst under visible light irradiation

In the quest to enhance photocatalytic performance, structural regulation and interface engineering stand out as effective strategies for amplifying active sites and fostering the separation of photogenerated electron-hole pairs. In this study, a pioneering approach was employed, utilizing a straightforward two-step calcination method to prepare a novel photocatalyst: porous graphite carbon nitride (g-C3N4, CN) nanosheets (NS) loaded with mesoporous cerium oxide (CeO2/CNNS). The distinctive architecture of CeO2/CNNS not only elevates the specific surface area and catalytic active sites but also facilitates efficient mass transfer. Experimental results and density functional theory (DFT) calculations corroborate the existence of an internal electric field (IEF) within the Z-scheme heterojunction formed by uniformly dispersed CeO2 and CNNS. This IEF proves pivotal in promoting charge separation and migration, thereby maintaining robust redox capabilities. Under visible light irradiation, CeO2/CNNS demonstrates an impressive 4.2-fold increase in the hydrogen production rate compared to bulk g-C3N4 (BCN), coupled with a 48.5% boost in the photocatalytic degradation rate constant (k) of tetracycline (TC). This study not only unveils the innovative design of CeO2/CNNS but also paves the way for a fresh perspective on the design and preparation of multifunctional photocatalysts.

A triazine-based covalent organic framework decorated with cadmium sulfide for efficient photocatalytic hydrogen evolution from water

Construction of inorganic/organic heterostructures has been proven to be a very promising strategy to design highly efficient photocatalysts for solar driven hydrogen evolution from water. Herein, we report the preparation of a direct Z-scheme heterojunction photocatalyst by in situ growth of cadmium sulfide on a triazine-based covalent organic framework (COF). The triazine based-COF was synthesized by condensation reaction of precursors 1,3,5-tris-(4-formyl-phenyl) triazine (TFPT) and 2,5-bis-(3-hydroxypropoxy) terephthalohydrazide (DHTH), termed as TFPT-DHTH-COF. Widely distributed nitrogen atoms throughout TFPT-DHTH-COF skeletons serve as anchoring sites for strong interfacial interactions with CdS. The CdS/TFPT-DHTH-COF composite showed a hydrogen evolution rate of 15.75 mmol h−1 g−1, which is about 75 times higher than that of TFPT-DHTH-COF (0.21 mmol h−1 g−1) and 3.4 times higher than that of CdS (4.57 mmol h−1 g−1). With the properly staggered band alignment and strong interfacial interaction between TFPT-DHTH-COF and CdS, a Z-scheme charge transfer pathway is achieved. The mechanism has been systematically analyzed by steady state and time-resolved photoluminescence measurements as well as in situ irradiated X-ray photoelectron spectroscopy.

Transient-State Self-Bipolarized Organic Frameworks of Single Aromatic Units for Natural Sunlight-Driven Photosynthesis of H2 O2.

Constructing π-conjugated polymer structures through covalent bonds dominates the design of organic framework photocatalysts, which significantly depends on the selection of multiple donor-acceptor building blocks to narrow the optical gap and increase the lifetimes of charge carriers. In this work, self-bipolarized organic frameworks of single aromatic units are demonstrated as novel broad-spectrum-responsive photocatalysts for H2 O2 production. The preparation of such photocatalysts is only to fix the aromatic units (such as 1,3,5-triphenylbenzene) with alkane linkers in 3D space. Self-bipolarized aromatic units can drive the H2 O2 production from H2 O and O2 under natural sunlight, wide pH ranges (3.0-10.0) and natural water sources. Moreover, it can be extended to catalyze the oxidative coupling of amines. Experimental and theoretical investigation demonstrate that such a strategy obeys the mechanism of through-space π-conjugation, where the closely face-to-face overlapped aromatic rings permit the electron and energy transfer through the large-area delocalization of the electron cloud under visible light irradiation. This work introduces a novel design concept for the development of organic photocatalysts, which will break the restriction of conventional through-band π-conjugation structure and will open a new way in the synthesis of organic photocatalysts.

Efficient Z scheme-type II charge transfer on the interfaces of PAN/ZnO/CdIn2S4 for the enhanced photocatalytic hydrogen generation

The CdIn2S4/xZnO (CIS/xZnO) and CdIn2S4/12.3ZnO-PANx (CIS/12.3ZnO-PANx, PAN is polyacrylonitrile) photocatalysts were prepared and their activities in photocatalytic water splitting for hydrogen production were studied. Their physicochemical properties were determined by XRD, SEM, TEM, XPS, UV–vis and PEC. The photocatalytic hydrogen evolution under the irradiation with full spectrum light was carried out to evaluate its photocatalytic activity and stability. The catalyst CIS/12.3ZnO-PAN30 exhibits the H2 production rate of 4.31 mmol g−1 h−1, ∼61.5 and 5.8 times that of PAN (0.07 mmol g−1 h−1) and CIS/12.3ZnO (0.74 mmol g−1 h−1), respectively. EPR, VB-XPS, Mott-Schottky analysis illustrate that the Z scheme-type II photo carriers transfer path is formed on the interfaces of the PAN/ZnO/CIS in the CIS/12.3ZnO-PAN30 composite, which is more favorable to the spatial separation and migration of photogenerated carriers with the light irradiation, thus significantly increasing the activity of the photocatalytic production. This work supplies a feasible method for preparation of novel ternary organic-inorganic hybrid photocatalysts.

Au@ZnS core–shell nanoparticles decorated 3D hierarchical porous TiO2 photocatalysts for visible-light-driven CO2 reduction into CH4

Hereby, the core–shell structured Au@ZnS nanoparticles were precipitated on three-dimensionally ordered macro-mesoporous TiO2 (Au@ZnS/3DOMm-TiO2) by GBMR/P method. The slow photon effect of 3DOM structure leads to increase the light trapping and absorption efficiency. The hierarchical porous structure improves the specific surface area of the carrier, providing a larger internal void for desorption of reaction products and additional activation sites for the CO2 reduction. In the all-solid Z-scheme system, electrons are transferred along the direction from TiO2 to Au and finally to the surface of ZnS is realized to participate in the reaction of CO2 reduction. Under irradiation of visible light, ternary Au@ZnS/3DOMm-TiO2-2 catalyst exhibits the highest catalytic activity for CO2 photoreduction with H2O, i.e., the formation rate and selectivity of CH4 product is 33.2 µmol g-1h−1 and 91.5 %, respectively. The design of Z-scheme heterojunctions on 3D macro-mesoporous oxide surfaces are expected to expand new ideas for the preparation of efficient photocatalysts.

Benzene-Linked Polymeric Carbon Nitride for Enhanced Photocatalytic Hydrogen Production.

Cross-linking with functional molecular species in polymeric carbon nitride (PCN) could offer a positive strategy that tunes its molecular structure with excellent conductivity to improve photocatalytic activity. Herein, the benzene ring-cross-linked photocatalyst is obtained via the polymerization of urea, melamine, and trimesic acid. Benzene ring-cross-linked PCN narrows the band gap and augments the push-pull effect of carriers, thus enhancing visible light harvesting and transfer easiness of photogenerated electron/hole pairs. Notably, the amount of trimesic acid was optimized during the benzene ring-cross-linked photocatalyst preparation (marked as 01T/A-CN, 02T/A-CN, and 03T/A-CN). Among them, 02T/A-CN photocatalyst achieved an excellent hydrogen production rate of 1931 μmol/h·g, which is higher than that of CN under visible light and beyond most reported. Theoretical calculations further confirmed that the introduction of benzene ring significantly reduces the band gap of PCN, bringing the delocalized electron, a longer intramolecular electron transition distance, and molecular bending. All those factors made benzene ring-cross-linked PCN with improved photocatalytic hydrogen production under visible light irradiation.

One-step synthesis of a diverting erythrocyte-like heterojunction and the augmented activity of wastewater treatment: Morphology modulation, theoretical calculations and mechanism explanation

As a green and sustainable technology, semiconductor photocatalysis mediated by heterojunction has shown great potential in the removal of organic pollutants from water environment. Yet, the nugatory recombination of photogenerated carriers induced by strong Coulombic forces lead to inferior photoactivity of semiconductor photocatalysts. In this paper, the erythrocyte-like composite (BiBrW) was designed to drive Z-type separation of photogenerated carriers through heterojunction interface by tight coupling between BiOBr and Bi2WO6. Combined with the results of characterizations, CTAB used in the synthesis process not only provides a bromine source but also serves as a surfactant to modulate the morphology of Bi2WO6 from petal-like to erythrocyte-like morphology. In contrast with the BiOBr/Bi2WO6 material fabricated via the in-situ growth method, the BiBrW composite displayed a uniform erythrocyte-like morphology with fewer grain boundaries by lamellar stacking of nanosheets. The combined effect of the construction of heterojunction and lessened grain boundaries endowed the BiBrW composite with augmented physicochemical properties, thereby enhancing its photocatalytic removal performance for various contaminants. Based on theoretical calculations, HPLC-MS tests and toxicity analysis, the reaction sites, degradation pathway and toxic evolution of ciprofloxacin (CIP) during the process of photodegradation were thoroughly elucidated, respectively. Moreover, the BiBrW catalyst still exhibits significant degradation performance for CIP under the excitation of natural sunlight. For different water qualities and distinct target pollutants (2-sec-butyl-4,6-dinitrophenol (DNBP), tetracycline (TC) and bisphenol A (BPA)), the catalyst maintains excellent photocatalytic removal capabilities, reflecting the superior universality of BiBrW catalyst. This research proposed novel mentality for preparation of heterojunction photocatalysts with less grain boundaries to assist in restoration of water environment.

Photocatalytic Water Splitting for H2 Production via Two‐electron Pathway

AbstractIn response to energy and environmental crises, solar‐driven pure water splitting is a promising way to produce and store renewable energy sources without environmental pollution. Photocatalytic water splitting via two‐electron pathway (2H2O→H2+H2O2) is a more kinetically favorable way to produce H2 compared with traditional four‐electron pathway. Although numerous efforts have been devoted to investigate the application of two‐electron pathway water splitting, drawbacks still inhibit the efficiency of H2 generation. This review discusses the mechanism and challenges of photocatalytic water splitting via a two‐electron pathway. Then, recent developments in novel photocatalyst preparation and modification strategies for effective H2 generation via two‐electron pathway were discussed, such as morphology and structure modulation, elemental doping, co‐catalyst loading, and heterostructure construction. In addition, the development of stepwise two‐electron pathway which further decomposed H2O2 and release O2 was also introduced. Appropriate co‐catalyst with high H2O2 decomposition activity that is essential for stepwise process was discussed. Finally, challenges and opportunities for commercial application of photocatalytic water splitting via two‐electron pathway were briefly outlined.

Boosting photocatalytic NO oxidation mediated by high redox charge carriers from visible light-driven C3N4/UiO-67 S-scheme heterojunction photocatalyst

The construction of CN/UiO-67 (CNU) S-scheme heterojunction composites through in situ formation of UiO-67 on carbon nitride (C3N4) helps to address the limitations of carbon nitride (CN) in photocatalytic NO elimination. The optimized CNU3 demonstrates superior photocatalytic efficiency, which is attributed to electronic channels constructed by Zr-N bonds and S-scheme electron transport mechanism, effectively promoting the efficient separation of photogenerated charge carriers with high redox potentials. Density Functional Theory (DFT) calculations reveal redistributed electronic orbitals in CNU3, with progressive and continuous energy levels near the Fermi level, which bolsters electronic conduction. Comprehensive quenching experiments, Electron Paramagnetic Resonance (EPR), and in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS) analyses highlight a synergistic interplay of electrons, holes, and superoxide radicals in CNU3, inhibiting the generation of toxic nitrogen oxide intermediates and culminating in highly efficient photocatalytic NO oxidation. This study not only elucidates the mechanisms underpinning the enhanced performance of CNU3 heterojunctions but also offers new perspectives on the preparation and interfacial charge separation of heterojunction photocatalysts.