Improved charge transfer by size-dependent plasmonic Au on C3N4 for efficient photocatalytic oxidation of RhB and CO2 reduction

Construction of Au-modified CN-based donor-acceptor system coupled with dual photothermal effects for efficient photoreduction of carbon dioxide

Conversion of CO2 into high value-added fuels through the photothermal effect is an effective approach for utilizing solar energy. In this study, we prepared the CN-based photocatalyst Py-CTN-Au with both donor-acceptor (D-A) system and dual photothermal effects using a simple two-step method involving calcination and photo-deposition. Real-time monitoring with a thermal imaging camera revealed that Py-CTN-Au0.5 achieved a maximum stable temperature of 180 °C, which was approximately 1.2 times higher than that of Py-CTN (155 °C) and 1.9 times higher than that of g-CN (95 °C) under the same reaction conditions. Under the optimized reaction conditions, Py-CTN-Au0.5 exhibited a CO release rate of 30.59 umol g-1 after 4 h of reaction, which was 7.3 times higher than that of pure g-CN (4.18 umol g-1). The D-A system not only facilitated the separation and transformation of charge carriers but also induced a photothermal effect to accelerate the photoreduction of CO2. Additionally, the cocatalyst Au nanoparticles (Au NPs) further enhanced the charge carrier dynamics and photothermal effect by increasing the built-in electric field intensity and localized surface plasmon resonance (LSPR) effect, respectively. The dual photothermal effects resulting from the non-radiative photon conversion of the D-A structure and the Au NPs LSPR effect, along with the enhanced charge carrier dynamics, catalyzed the efficient photoreduction of CO2. DFT simulations were used to confirm the effect of D-A system and Au NPs. In-situ FTIR results demonstrated that the synergistic photothermal effect promoted the formation of the key intermediate species COOH*, which is beneficial for the photocatalytic reduction of CO2. This study provides valuable insights into the multiple photothermal synergistic effects in photocatalytic reactions.

Electron Structure Tuned Oxygen Vacancy-Rich AuPd/CeO2 for Enhancing 5-Hydroxymethylfurfural Oxidation

The design of high activity catalyst for the efficiently conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA) gains great interest. The rationally tailoring of electronic structure directly affects the interaction between catalysts and organic substrates, especially molecular oxygen as the oxidant. This work, the bimetallic catalysts AuPd/CeO2 were prepared by the combining method of chemical reduction and photo-deposition, effectively concerting charge between Au and Pd and forming the electron-rich state of Au. The increasing of oxygen vacancy concentration of CeO2 by acidic treatment can facilitate the adsorption of HMF for catalysts and enhance the yield of FDCA (99.0 %). Moreover, a series of experiment results combining with density functional theory calculation illustrated that the oxidation performance of catalyst in HMF conversion was strongly related to the electronic state of interfacial Au-Pd-CeO2. Furthermore, the electron-rich state sites strengthen the adsorption and activation of molecular oxygen, greatly promoting the elimination of β-hydride for the selective oxidation of 5-hydroxymethyl-2-furancarboxylic acid (HMFCA) to FDCA, accompanied with an outgoing FDCA formation rate of 13.21 mmol ⋅ g-1 ⋅ min-1 at 80 °C. The perception exhibited in this research could be benefit to understanding the effects of electronic state for interfacial sites and designing excellent catalysts for the oxidation of HMF.

g-C3N4 modified with non-precious metal Al with LSPR as an efficient visible light catalyst

The issue of water pollution has emerged as a formidable challenge, prompting a pressing need for solutions. The utilization of metal nanoparticles with surface plasmon resonance and semiconductor composite photocatalysts is regarded as a highly effective approach to solve this problem. g-C3N4 is an effective catalyst for the degradation of organic pollutants. Its photocatalytic performance is usually enhanced by the use of the noble metal Au Ag. However, the high cost of these materials limits their application. In this study, we present the synthesis of Al NPs/g-C3N4 nanocomposites using the bridging effect of ligands. The characterized of transmission electron microscopy (TEM), X-ray diffractometer (XRD) and ultraviolet-visible spectroscopy (UV-Vis) proved that Al NPs/g-C3N4 with a wider light absorption range were successfully synthesized. The effects of ligands, (glutathione (GSH), glutamic acid (GAG), and cysteine (CYS)), Al diameter (40 to 200 nm) and the ratio of Al to g-C3N4 (1:1 to 5:1) on the photocatalytic degradation of methylene blue (MB) by Al NPs/g-C3N4 were also evaluated. The results showed that the optimum degradation efficiency of Al NPs/g-C3N4 for MB at 5 mg/L reached 100% within 60 min, which was 11 times higher than that of pure g-C3N4. The principal analysis of Al enhancing the photocatalytic performance of g-C3N4 was studied through transient photocurrent spectroscopy (TPC), electrochemical impedance spectroscopy (EIS), and steady-state transient fluorescence spectroscopy (PL). The results confirmed that hot carriers generated by localized surface plasmon resonance (LSPR) of Al nanoparticles increase the carrier concentration. In addition, the Schottky barrier generated by Al and g-C3N4 could also improve the carrier separation rate and increase the carrier lifetime. This work is expected to solve the problem of organic wastewater treatment and lay the foundation for subsequent research on photocatalysis.

Size Effect of Cu Nanoparticles in Cu/g-C3N4 Composites on Properties for Highly Efficient Photocatalytic Reduction of CO2 to Methanol

The main goal of this work is to develop cheap photocatalysts for the efficient photocatalytic reduction of CO2 to methanol with water. A series of composites of Cu/g-C3N4 were prepared via a solvothermal method. Copper nanoparticle (Cu NP) size in Cu/g-C3N4 can be easily controlled by adjusting the synthesis temperature. The Cu/g-C3N4 material with the proper size of Cu NP (CuCN-100) had the best photocatalytic property (675 μmol·g-1·h-1) in reducing the amount of CO2 to methanol at room temperature under normal pressure. The particle size of Cu NPs is the key factor to improve the catalytic activity and stability because of the improved transfer and separation of photogenerated charges with the small Cu NPs. Although the sample with large Cu NPs (CuCN-200) initially gave a better activity than that of CuCN-100 due to the formation of double heterojunction, its activity was thoroughly lost after two runs resulting from the continuous photocorrosion. This work provides a valuable insight for preparing efficient semiconductor-metal photocatalysts.

Recent progress of cocatalysts loaded on carbon nitride for selective photoreduction of CO2 to CH4

A photocatalytic system driven by solar light is one of the promising strategies for converting CO₂ into valuable energy. The reduction of CO₂ to CH₄ is widely studied since CH₄ has a high energy density as the main component of nonrenewable natural gas. Therefore, it is necessary to develop semiconductor materials with high photocatalytic activity and CH₄ selectivity. Graphitic carbon nitride (g-C₃N₄/CN) has attracted widespread attention for photocatalytic CO₂ reduction due to its excellent redox ability and visible light response. A hybrid system constructed by loading cocatalysts on g-C₃N₄ can significantly improve the yield of target products, and serve as a general platform to explore the mechanism of the CO₂ reduction reaction. Herein, we briefly introduce the theory of selective CO₂ photoreduction and the basic properties of cocatalysts. Then, several typical configurations and modification strategies of cocatalyst/CN systems for promoting CH₄ selective production are presented in detail. In particular, we systematically summarize the application of cocatalyst/CN composite photocatalysts in the selective reduction of CO₂ to methane, according to the classification of cocatalysts (monometal, bimetal, metal-based compound, and nanocarbon materials). Finally, the challenges and perspectives for developing cocatalyst/g-C₃N₄ systems with high CH₄ selectivity are presented to guide the rational design of catalysts with high performance in the future.

Recent Trends in Plasmon-Assisted Photocatalytic CO2 Reduction

Direct photocatalytic reduction of CO₂ has become an highly active field of research. It is thus of utmost importance to maintain an overview of the various materials used to sustain this process, find common trends, and, in this way, eventually improve the current conversions and selectivities. In particular, CO₂ photoreduction using plasmonic photocatalysts under solar light has gained tremendous attention, and a wide variety of materials has been developed to reduce CO₂ towards more practical gases or liquid fuels (CH₄ , CO, CH₃ OH/CH₃ CH₂ OH) in this manner. This Review therefore aims at providing insights in current developments of photocatalysts consisting of only plasmonic nanoparticles and semiconductor materials. By classifying recent studies based on product selectivity, this Review aims to unravel common trends that can provide effective information on ways to improve the photoreduction yield or possible means to shift the selectivity towards desired products, thus generating new ideas for the way forward.

Plasmonic Photocatalysis for CO2 Reduction: Advances, Understanding and Possibilities

Plasmonic photocatalysis for CO₂ reduction is attracting increasing attention due to appealing properties and great potential for real applications. In this review, the fundamentals of plasmonic photocatalysis and the most recent developments regarding its application in driving CO₂ reduction are reported. Firstly, we present the review on the mechanism of plasmonic photocatalytic CO₂ reduction, the energy transfer of plasmon, and the CO₂ reduction process on the catalyst surface. Then, the modulation on the plasmonic nanostructures and also the semiconductor counterpart to regulate CO₂ photoreduction is discussed. Next, the influence of the core-shell structure and the interface between the plasmonic metal and semiconductor on the CO₂ photoreduction performance is also outlined. In addition, the latest progress on the emerging direction regarding the plasmonic photocatalysis for methane dry reforming with CO₂ is especially emphasized. Finally, a summary on the challenges and prospects of this promising field are provided.

Design and application of g-C3N4-based materials for fuels photosynthesis from CO2 or H2O based on reaction pathway insights

Photocatalytic CO2 reduction reaction (CRR) and hydrogen evolution reaction (HER) based on graphitic carbon nitride (g-C3N4) that is regarded as the metal-free "holy grail" photocatalyst, provide promising strategies for producing next-generation fuels, contributing to achieving carbon neutrality, alleviating energy and environment crisis. However, the activity of CRR and HER over g-C3N4 leaves much to be desired. Therefore, numerous studies have sprung up to enhance photoactivity. A comprehensive understanding of the CRR and HER reaction pathways is crucial for designing g-C3N4-based materials, further promoting efficient fuel production. Different from previous reviews that focus on g-C3N4 modification from the viewpoint of material science. In this review, we divided the multistep processes of CRR and HER into five reaction pathways and summarized the latest advances for improving each pathway of fuels synthesis through CRR or HER. Meanwhile, the existing bottleneck issues of each step were also discussed. Finally, comprehensive conclusions, including the remaining challenges, outlooks, etc., for CRR and HER over g-C3N4 were put forward. We are sure that this review will conduce to the understanding of the structure-activity relationship between CRR, HER processes, and g-C3N4 structure, which can provide the reference for developing high-powered photocatalysts, not confined to g-C3N4.

Crystal Faces-Tailored Oxygen Vacancy in Au/CeO2 Catalysts for Efficient Oxidation of HMF to FDCA

Developing an efficient catalyst to upgrade 5-hydroxymethylfurfural (HMF) to high-value-added downstream chemicals is of great significance in biomass conversion. Nanorod (110)-, nanocube (100)-, and nanooctaheron (111)-CeO₂ -supported Au nanoparticles were prepared to investigate the intrinsic effect of CeO₂ crystal faces on the oxidation of HMF to 2,5-furandicarboxylic acid (FDCA). The experimental results and density functional theory calculation revealed that the concentration of oxygen vacancy (V_O ) for exposed specific crystal faces was crucial to the oxygen adsorption ability, and Au/nanorod-CeO₂ with the highest V_O concentration promoted the formation of more oxygen active species (superoxide radical) on CeO₂ (110) crystal face than (100) and (111) crystal faces. Besides, the higher V_O concentration could provide a strong adsorption ability of HMF, greatly boosting the activation of HMF. Thus, these results led to a superior catalytic activity for HMF oxidation over Au/nanorod-CeO₂ (FDCA yield of 96.5 %). In-situ Fourier-transform (FT)IR spectroscopy uncovered the HMF oxidation pathway, and the possible catalytic mechanism was proposed. The deep insight into the role of regulation for crystal faces provides a basis for the rational design of highly active facets for the oxidation of HMF and related reactions.

Few-layer porous carbon nitride anchoring Co and Ni with charge transfer mechanism for photocatalytic CO2 reduction

The low specific surface area and low charge transfer efficiency of conventional graphite carbon nitride (g-C₃N₄) are the main obstacles to its application in photocatalytic CO₂ reduction. In this paper, graphite carbon nitride was protonated by phosphoric acid (H₃PO₄), and a new few-layer porous carbon nitride was prepared by intercalation polymerization with doping bimetal in the cavity of g-C₃N₄. Under visible light irradiation, the CO formation rate of Co/Ni co-doped g-C₃N₄ can reach 13.55 μmol g^-1 h^-1, which was 3.9 times higher than that of g-C₃N₄ (3.49 μmol g^-1 h^-1). The density functional theory (DFT) calculations showed that the addition of Co and Ni in the cavity of g-C₃N₄ can induce bimetallic synergistic regulation of the electronic structure, thus improving the separation efficiency of charges and visible light capture ability of g-C₃N₄. Our work has great reference value for designing and synthesizing novel bimetallic co-doped g-C₃N₄ photocatalytic materials.

Hybrid Plasmonic Nanomaterials for Hydrogen Generation and Carbon Dioxide Reduction

The successful development of artificial photosynthesis requires finding new materials able to efficiently harvest sunlight and catalyze hydrogen generation and carbon dioxide reduction reactions. Plasmonic nanoparticles are promising candidates for these tasks, due to their ability to confine solar energy into molecular regions. Here, we review recent developments in hybrid plasmonic photocatalysis, including the combination of plasmonic nanomaterials with catalytic metals, semiconductors, perovskites, 2D materials, metal-organic frameworks, and electrochemical cells. We perform a quantitative comparison of the demonstrated activity and selectivity of these materials for solar fuel generation in the liquid phase. In this way, we critically assess the state-of-the-art of hybrid plasmonic photocatalysts for solar fuel production, allowing its benchmarking against other existing heterogeneous catalysts. Our analysis allows the identification of the best performing plasmonic systems, useful to design a new generation of plasmonic catalysts.

Renewable biomass-derived carbon-supported g-C3N4 doped with Ag for enhanced photocatalytic reduction of CO2

Constructing noble metal-doped g-C₃N₄/carbon composites is a feasible route to overcome the intrinsic drawbacks of pristine g-C₃N₄ for enhanced activity of CO₂ photoreduction. Herein, a novel Ag-doped g-C₃N₄/biomass-derived carbon composite with hollow bird's nest-like (Ag-g-C₃N₄/BN-C) is designed and prepared via a simple yet effective one-step pyrolysis method. In the Ag-g-C₃N₄/BN-C, the highly-dispersed Ag nanoparticles (20-30 nm) with the surface plasmon resonance (SPR) effect act as a significant cocatalyst not only to efficiently trap the photogenerated electrons from g-C₃N₄ to boost the separation of photogenerated electron-hole pairs but also to produce additional active "hot electrons", while the conductive quasi-spherical hollow structure of BN-C doubles the specific surface area with multiple reflections of light, providing abundant active sites and more utilization efficiency of light energy. As a result, the Ag-g-C₃N₄/BN-C exhibits a remarkably enhanced CO evolution rate of 33.3 μmol·g^-1·h^-1 without addition of any sacrificial reagents and photosensitizers, superior to those of both the pristine g-C₃N₄ and many reported g-C₃N₄-based counterparts. The findings of this work demonstrate a good indication for integrating g-C₃N₄ with SPR-dependence noble metal and renewable biomass-derived carbon for enhanced CO₂ photoreduction, which may be extended to modify other semiconductor materials for more photocatalytic applications with enhanced activity.

Highly Efficient Electrocatalytic N2 Reduction to Ammonia over Metallic 1T Phase of MoS2 Enabled by Active Sites Separation Mechanism

The 1T phase of MoS2 has been widely reported to be highly active toward the hydrogen evolution reaction (HER), which is expected to restrict the competitive nitrogen reduction reaction (NRR). However, in this work, a prototype of active sites separation over 1T-MoS2 is proposed by DFT calculations that the Mo-edge and S atoms on the basal plane exhibit different catalytic NRR and HER selectivity, and a new role-playing synergistic mechanism is also well enabled for the multistep NRR, which is further experimentally confirmed. More importantly, a self-sacrificial strategy using g-C3 N4 as templates is proposed to synthesize 1T-MoS2 with an ultrahigh 1T content (75.44%, named as CNMS, representing the composition elements of C, N, Mo, and S), which yields excellent NRR performances with an ammonia formation rate of 71.07 µg h-1 mg-1 cat. at -0.5 V versus RHE and a Faradic efficiency of 21.01%. This work provides a promising new orientation of synchronizing the selectivity and activity for the multistep catalytic reactions.

Molecular Self-Assembly of Oxygen Deep-Doped Ultrathin C3N4 with a Built-In Electric Field for Efficient Photocatalytic H2 Evolution

Heteroatom-doped carbon nitride (C₃N₄) with a built-in electric field can reinforce the carrier separation; however, the stability will be greatly reduced due to the loss of surface-doped atoms. Here, molecule self-assembly, as a facile bottom-up approach, is explored for the synthesis and oxygen doping of C₃N₄. The obtained C₃N₄ presents a porous and ultrathin structure and oxygen deep-doping, which generate abundant nitrogen vacancies and a stable built-in electric field. Toward photocatalytic hydrogen evolution, the ultrathin and oxygen deep-doped C₃N₄ exhibits a 3.5-fold higher activity than bulk C₃N₄ under simulated sunlight, and 3.6 times higher stability than the oxygen surface-doped counterpart within five cycles. Femtosecond transient absorption spectroscopy indicates the improved carrier separation, and density functional theory (DFT) calculation reveals the promoted H₂O adsorption and activation under the built-in electric field, which contribute to the excellent photocatalytic performance of oxygen deep-doped ultrathin C₃N₄.

Fabrication and photocatalytic activity of graphitic-C3N4 quantum dots-decorated basic zinc carbonate prepared by a co-precipitation method

Graphitic carbon nitride quantum dots (CNQDs) with a high quantum yield (up to 43%) were synthesized by incorporating the unique organic functional group of barbituric acid into the framework of the carbon nitride structure by supramolecular pre-organization. The CNQDs were introduced onto the surface of basic zinc carbonate (BZC) by co-precipitation. The resulting CNQDs/BZC composite showed that the degradation efficiency of tetracycline was 2.4 times higher than that of ZnO. The Z-scheme mechanism for the as-prepared sample was proposed for the enhanced photocatalytic degradation rate. The ˙O₂^- and ˙OH radicals played major roles due to the suitable bandgap. Finally, the formation and possible photocatalytic mechanisms of the CNQDs/BZC composite are proposed.

Fabricating intramolecular donor-acceptor system via covalent bonding of carbazole to carbon nitride for excellent photocatalytic performance towards CO2 conversion

Photocatalytic conversion of CO₂ into hydrocarbon fuels is an ideal technology of mitigating greenhouse effect caused by excessive emission of CO₂. However, the high recombination rate of electron-hole pairs and limited charge carriers transport speed constrained the catalytic performance of many semiconductor catalysts. In this contribution, a series of carbon nitride (g-CN) samples with intramolecular donor-acceptor (D-A) system were successfully prepared by introducing organic donor into their structures. Characterization results confirmed that carbazole was successful connected to the structure of g-CN via chemical bond. The formation of intramolecular D-A system greatly enlarged the light response region of g-CN-xDbc. In addition, a new charge transfer transition mode was formed in g-CN-0.01Dbc due to the incorporation carbazole, which enable it to use light with energy lower than the intrinsic absorption of g-CN. Meanwhile, the D-A structure led to the spatial separation of electrons and holes in g-CN-xDbc and significantly decreased the recombination rate of electron-hole pairs. The g-CN-0.01Dbc presented the best catalytic performance and the CO evolution rate was 9.6 times higher than that of g-CN. Moreover, the reaction was performed in water without any additive, which made it green and sustainable. DFT simulation confirmed the D-A structure and charge carrier migration direction in the prepared samples.

Recent advances in graphite carbon nitride-based nanocomposites: structure, antibacterial properties and synergies

Bacterial infections and transmission threaten human health and well-being. Graphite carbon nitride (g-C₃N₄), a promising photocatalytic antibacterial nanomaterial, has attracted increasing attention to combat bacterial transmission, due to the outstanding stability, high efficiency and environmental sustainability of this material. However, the antibacterial efficiency of g-C₃N₄ is affected by several factors, including its specific surface area, rapid electron/hole recombination processes and optical absorption properties. To improve the efficiency of the antibacterial properties of g-C₃N₄ and extend its range of applications, various nanocomposites have been prepared and evaluated. In this review, the advances in amplifying the photocatalytic antibacterial efficiency of g-C₃N₄-based nanocomposites is discussed, including different topologies, noble metal decoration, non-noble metal doping and heterojunction construction. The enhancement mechanisms and synergistic effects in g-C₃N₄-based nanocomposites are highlighted. The remaining challenges and future perspectives of antibacterial g-C₃N₄-based nanocomposites are also discussed.

Cocatalysts from types, preparation to applications in the field of photocatalysis

With the rapid development of society, the burden of energy and the environment is becoming more and more serious. Photocatalytic hydrogen production, the photosynthesis of organic fuel, and the photodegradation of pollutants are three effective ways to reduce these burdens using semiconductor photocatalysts. To improve the reaction efficiency of photocatalysts, a small amount of cocatalyst is often added when photocatalysts participate in the synthesis or decomposition reaction. The addition of this small amount of cocatalyst is like a finishing touch, significantly increasing the activity of the photocatalysts. However, in our common study of photocatalysis, we often pay attention to the study of photocatalysts but ignore the study of cocatalysts. Herein, we summarize the recent application research on cocatalysts in the field of photocatalysis, starting from the types, preparation methods, and reaction mechanisms among others, to remind researchers of the matters needing attention when using cocatalysts.

Multichannel Electron Transmission and Fluorescence Resonance Energy Transfer in In2S3/Au/rGO Composite for CO2 Photoreduction

Efficient electron transmission is an important step in the process of CO₂ photoreduction. In this paper, a multi-interface-contacted In₂S₃/Au/reduced graphene oxide (rGO) photocatalyst with the fluorescence resonance energy transfer (FRET) mechanism has been successfully prepared by the solvothermal, self-assembly, and hydrothermal reduction processes. Photocatalytic CO₂ reduction experiments showed that the In₂S₃/Au/rGO (IAr-3) composite exhibited excellent photoreduction performance and photocatalytic stability. The yields of CO and CH₄ obtained after the photoreduction process with IAr-3 as the catalyst were around 4 and 6 times higher than those of pure In₂S₃, respectively. Photoelectrochemical analysis showed that the multi-interface contact and FRET mechanism greatly improved the generation, transmission, and separation efficiency of carriers photogenerated within the photocatalyst. In situ FTIR test was applied to analyze the photocatalytic CO₂ reduction process. ¹³C isotope tracer test confirmed that the carbon source of CO and CH₄ was the CO₂ molecules in the photoreduction process rather than the decomposition of catalyst or TEOA. A potential enhanced photocatalytic mechanism has been discussed in total.

Constructed Z-Scheme g-C3N4/Ag3VO4/rGO Photocatalysts with Multi-interfacial Electron-Transfer Paths for High Photoreduction of CO2

Z-scheme g-C₃N₄/Ag₃VO₄/reduced graphene oxide (rGO) photocatalysts with multi-interfacial electron-transfer paths enhancing CO₂ photoreduction under UV-vis light irradiation were successfully prepared by a hydrothermal process. Transmission electron microscope images displayed that the prepared photocatalysts have a unique 2D-0D-2D ternary sandwich structure. Photoelectrochemical characterizations including TPR, electrochemical impedance spectroscopy, photoluminescence, and linear sweep voltammetry explained that the multi-interfacial structure effectively improved the separation and transmission capabilities of photogenerated carriers. Electron spin resonance spectroscopy and band position analysis proved that the electron-transfer mode of g-C₃N₄/Ag₃VO₄ meets the Z-scheme mechanism. The introduction of rGO provided more electron-transfer paths for the photocatalysts and enhanced the stability of Ag-based semiconductors. In addition, the π-π conjugation effect between g-C₃N₄ and rGO further improved the generation and separation efficiency of photogenerated electron-hole pairs. Then, the multiple channels (Ag₃VO₄ → CN, Ag₃VO₄ → rGO → CN, and rGO → CN) due to the 2D-0D-2D structure greatly improving the photocatalytic CO₂ reduction ability have been discussed in detail.

Boosting charge carrier separation efficiency by constructing an intramolecular DA system towards efficient photoreduction of CO2

The charge carrier excitation–recombination process between the donor and acceptor, and the photocatalytic reduction of CO₂ to CO over CN based DA composites.

Fabrication of novel carbon species into porous g-C3N4 nanosheet frameworks with enhanced photocatalytic performance

A novel carbon-species-modified g-C₃N₄ nanosheet photocatalyst was successfully obtained and displayed superior photocatalytic degradation performance.

The preparation of Al2O3/g-C3N4 composites in aluminum–water self-assembly system and its improved photocatalytic properties

The aluminum alloy is used as the aluminum source, together with melamine and cyanuric acid, in a water reaction system to obtain the precursor of Al2O3/g-C3N4 through self-assembly in one step, and then calcined to obtain the Al2O3/g-C3N4 composite photocatalytic material.

Construction of a CsPbBr3 modified porous g-C3N4 photocatalyst for effective reduction of CO2 and mechanism exploration

A P-CN/CsPbBr₃ photocatalyst with a lamellar porous structure was prepared by a high temperature calcination and freeze drying method, and it exhibited superior CO₂ reduction performance under the conditions of full spectrum irradiation.

The influence of ZnO loading amount on the photocatalytic performance of Fe3O4@SiO2@ZnO–Ag composites toward the degradation of organic pollutants and hydrogen evolution

Magnetically reusable Fe3O4@SiO2@ZnO-Ag with well-designed core-shell structure, controllable ZnO loading amount and excellent photocatalytic ability toward organic pollutants degradation and hydrogen evolution were synthesized.

Size-dependent strong metal-support interaction in TiO2 supported Au nanocatalysts

The strong metal-support interaction (SMSI) has long been studied in heterogonous catalysis on account of its importance in stabilizing active metals and tuning catalytic performance. As a dynamic process taking place at the metal-support interface, the SMSI is closely related to the metal surface properties which are usually affected by the size of metal nanoparticles (NPs). In this work we report the discovery of a size effect on classical SMSI in Au/TiO₂ catalyst where larger Au particles are more prone to be encapsulated than smaller ones. A thermodynamic equilibrium model was established to describe this phenomenon. According to this finding, the catalytic performance of Au/TiO₂ catalyst with uneven size distribution can be improved by selectively encapsulating the large Au NPs in a hydrogenation reaction. This work not only brings in-depth understanding of the SMSI phenomenon and its formation mechanism, but also provides an alternative approach to refine catalyst performance.

Plasmonic Photocatalysts for Sunlight-Driven Reduction of CO2 : Details, Developments, and Perspectives

Plasmonic photocatalysis is among the most efficient processes for the photoreduction of CO₂ into valuable fuels. The formation of localized surface plasmon resonance (LSPR), energy transfer, and surface reaction are the significant steps in this process. LSPR plays an essential role in the performance of plasmonic photocatalysts as it promotes an excellent, light absorption over a broad wavelength range while simultaneously facilitating an efficient energy transfer to semiconductors. The LSPR transfers energy to a semiconductor through various mechanisms, which have both advantages and disadvantages. This work points out four critical features for plasmonic photocatalyst design, that is, plasmonic materials, size, shape of plasmonic nanoparticles (PNPs), and the contact between PNPs and semiconductor. Various developed plasmonic photocatalysts, as well as their photocatalytic performance in CO₂ photoreduction, are reviewed and discussed. Finally, perspectives of advanced architectures and structural engineering for plasmonic photocatalyst design are put forward with high expectations to achieve an efficient CO₂ photoreduction shortly.

Effective charge kinetics steering in surface plasmons coupled two-dimensional chemical Au/Bi2WO6-MoS2 heterojunction for superior photocatalytic detoxification performance

Developing and designing a rational heterojunction with efficient charge kinetics properties have been a research hotspot for improving photocatalytic performance. Herein, a surface plasmons coupled two-dimensional chemical Au/Bi₂WO₆-MoS₂ heterojunction was synthesized. In thus a system, Au nanoparticles are tightly attached to the sides of Bi₂WO₆ nanosheets, conducting a HEI effect with additional visible light response to inject "hot electrons" into Bi₂WO₆, resulting in additional charge generation. Meanwhile, few-layer MoS₂ nanosheets were chemically assembled onto ultrathin Bi₂WO₆ nanosheets via interfacial SO bonds to form a intimate 2D-2D nanojunction, the separated and injected electrons on the surface of Bi₂WO₆ were further directional transfer to MoS₂ nanosheets through SO bonds for detoxification of heavy metal ions Cr(VI), and the corresponding holes left on Bi₂WO₆ nanosheets were applied for simultaneous degradation of tetracycline antibiotic. The photocatalytic detoxification activity of Au/Bi₂WO₆-MoS₂ was nearly 4.84, 3.47 and 1.90 times higher than that of pristine Bi₂WO₆, Au/Bi₂WO₆ and Bi₂WO₆-MoS₂ composites, which could be ascribed to the effective charge kinetics steering and well manipulation of charge flow by virtue of the rational structural and compositional features. This work provides a new perspective for the construction of high-activity detoxification photocatalysts through steering charge kinetics.

Metal-Free Enhanced Photocatalytic Activation of Dioxygen by g-C3N4 Doped with Abundant Oxygen-Containing Functional Groups for Selective N-Deethylation of Rhodamine B

To develop highly efficient heterogeneous photocatalysts for the activation of dissolved oxygen is very interesting in the field of green degradation of organic pollutants. In the paper, oxygen atom doped g-C3N4 (O-g-C3N4) was prepared via a facile chemical oxidation of g-C3N4 by peroxymonosulfate. X-ray photoelectron spectroscopy analysis suggests the oxidative treatment of g-C3N4 by peroxymonosulfate evidently increased atomic percentage of oxygen on O-g-C3N4 surface to 6.9% as compared with 1.8% for g-C3N4. Meanwhile, the doped oxygen atom mainly existed as carbonyl and carboxyl groups. Optical characterization indicates the introduction of oxygen improved the response of O-g-C3N4 to visible light, and more obviously, separation of photo-generated h+-e−. 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) probe measurement indicates the formation of O2•− was dramatically enhanced through activation of dioxygen by photo-generated electrons in the O-g-C3N4 photocatalytic system. Through high performance liquid chromatography (HPLC) and Liquid chromatography–mass spectrometry (LC-MS) analysis, it was found rhodamine B (RhB) photocatalytic degradation by O-g-C3N4 followed step by step N-deethylation reaction pathways induced by the formed O2•−, rather than the non-selective decomposition of the chromophore in RhB by other radicals, such as hydroxyl radicals. This study provides a facile method to develop oxygen atom doped g-C3N4 photocatalyst, and also clarifies its photocatalytic activation mechanism of molecular oxygen for N-deethylation reaction of RhB.

The Role of Fluorine in F-La/TiO2 Photocatalysts on Photocatalytic Decomposition of Methanol-Water Solution

F-La/TiO₂ photocatalysts were studied in photocatalytic decomposition water-methanol solution. The structural, textural, optical, and electronic properties of F-La/TiO₂ photocatalysts were studied by combination of X-ray powder diffraction (XRD), nitrogen physisorption, Ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis DRS), Electrochemical impedance spectroscopy (EIS), and X-ray fluorescence (XPS). The production of hydrogen in the presence of 2.8F-La/TiO₂ was nearly up to 3 times higher than in the presence of pure TiO₂. The photocatalytic performance of F-La/TiO₂ increased with increasing photocurrent response and conductivity originating from the higher amount of fluorine presented in the lattice of TiO₂.