Conjugated Electron Donor⁻Acceptor Hybrid Polymeric Carbon Nitride as a Photocatalyst for CO2 Reduction

Metal/Covalent Organic Framework Encapsulated Lead-Free Halide Perovskite Hybrid Nanocatalysts: Multifunctional Applications, Design, Recent Trends, Challenges, and Prospects

Perovskites are bringing revolutionization in a various fields due to their exceptional properties and crystalline structure. Most specifically, halide perovskites (HPs), lead-free halide perovskites (LFHPs), and halide perovskite quantum dots (HPs QDs) are becoming hotspots due to their unique optoelectronic properties, low cost, and simple processing. HPs QDs, in particular, have excellent photovoltaic and optoelectronic applications because of their tunable emission, high photoluminescence quantum yield (PLQY), effective charge separation, and low cost. However, practical applications of the HPs QDs family have some limitations such as degradation, instability, and deep trap states within the bandgap, structural inflexibility, scalability, inconsistent reproducibility, and environmental concerns, which can be covered by encapsulating HPs QDs into porous materials like metal-organic frameworks (MOFs) or covalent-organic frameworks (COFs) that offer protection, prevention of aggregation, tunable optical properties, flexibility in structure, enhanced biocompatibility, improved stability under harsh conditions, consistency in production quality, and efficient charge separation. These advantages of MOFs-COFs help HPs QDs harness their full potential for various applications. This review mainly consists of three parts. The first portion discusses the perovskites, halide perovskites, lead-free perovskites, and halide perovskite quantum dots. In the second portion, we explore MOFs and COFs. In the third portion, particular emphasis is given to a thorough evaluation of the development of HPs QDs@MOFs-COFs based materials for comprehensive investigations for next-generation materials intended for diverse technological applications, such as CO2 conversion, pollutant degradation, hydrogen generation, batteries, gas sensing, and solar cells. Finally, this review will open a new gateway for the synthesis of perovskite-based quantum dots.

Synergistic Enhancement of CO2 photoreduction through sulfur defects in (3D/2D) CdS-nanoflowers/CN Binary heterojunction photocatalyst under visible light

Global warming is the biggest threat to the entire world owing to the continuous release of greenhouse gases such as CO2 from various sources. Herein, we have utilized renewable energy for the conversion of CO2 to valuable feedstocks through a semiconductor-mediated photocatalytic system. The cadmium sulfide nanoflowers (CS-NFs) decorated graphitic carbon nitride (CN) through a solvothermal route to form a Z-scheme CSCN heterojunction. The as-synthesized material has been characterized by various spectroscopic and microscopic tools. The optimal CSCN-0.5 (1:0.5) photocatalyst achieves a CO production rate of 130.9 μmol g-1 under visible light irradiation of 4h (λ > 420 nm), doubling that of pristine CS-NFs and CN. CO, along with CH4 (3.4 μmol g-1) and C2H6 (2.9 μmol g-1), is the sole product detected. Experimental results indicate that the CSCN-0.5 photocatalyst spatially separates electron-hole pairs, suppresses charge carrier recombination, and maintains robust redox ability, enhancing CO2 photoreduction. The CO2 reduction mechanism over CSCN heterojunction was also studied through in-situ DRIFTS and electron spin resonance (ESR) measurements. Therefore, CSCN proves that it could be used as a robust photocatalyst for the CO2 reduction reactions towards C1 and C2 feedstocks.

Preparation of visible-light active MOFs-Perovskites (ZIF-67/LaFeO3) nanocatalysts for exceptional CO2 conversion, organic pollutants and antibiotics degradation

Modern industries rapid expansion has heightened energy needs and accelerated fossil fuel depletion, contributing to global warming. Additionally, organic pollutants present substantial risks to aquatic ecosystems due to their stability, insolubility, and non-biodegradability. Scientists are currently researching high-performance materials to address these issues. LaFeO3 nanosheets (LFO-NS) were synthesized in this study using a solvothermal method with polyvinylpyrrolidone (PVP) as a soft template. The LFO-NS demonstrate superior performance, large surface area and charge separation than that of LaFeO3 nanoparticles (LFO-NP). The LFO-NS performance is further upgraded by incorporating ZIF-67. Our results confirmed the ZIF-67/LFO-NS nanocomposite have superior performances than pure LFO-NP and ZIF-67. The integration of ZIF-67 has enhanced the charge separation and promote the surface area of LFO-NSwhich was confirmed by various characterization techniques including TEM, HRTEM, DRS, EDX, XRD, FS, XPS, FT-IR, BET, PL, and RAMAN. The 5ZIF-67/LFO-NS sample showed significant activities for CO2 conversion, malachite green degradation, and antibiotics (cefazolin, oxacillin, and vancomycin) degradation. Furthermore, stability tests have confirmed that our optimal sample very active and stable. Furthermore, based on scavenger experiments and the photocatalytic degradation pathways, it has been established that H+ and •O2- are vital in the decomposition of MG and antibiotics. Our research work will open new gateways to prepare MOFs-Perovskites nanocatalysts for exceptional CO2 conversion, organic pollutants and antibiotics degradation.

Recent developments, advances and strategies in heterogeneous photocatalysts for water splitting

Photocatalytic water splitting (PWS) is an up-and-coming technology for generating sustainable fuel using light energy. Significant progress has been made in the developing of PWS innovations over recent years. In addition to various water-splitting (WS) systems, the focus has primarily been on one- and two-steps-excitation WS systems. These systems utilize singular or composite photocatalysts for WS, which is a simple, feasible, and cost-effective method for efficiently converting prevalent green energy into sustainable H2 energy on a large commercial scale. The proposed principle of charge confinement and transformation should be implemented dynamically by conjugating and stimulating the photocatalytic process while ensuring no unintentional connection at the interface. This study focuses on overall water splitting (OWS) using one/two-steps excitation and various techniques. It also discusses the current advancements in the development of new light-absorbing materials and provides perspectives and approaches for isolating photoinduced charges. This article explores multiple aspects of advancement, encompassing both chemical and physical changes, environmental factors, different photocatalyst types, and distinct parameters affecting PWS. Significant factors for achieving an efficient photocatalytic process under detrimental conditions, (e.g., strong light absorption, and synthesis of structures with a nanometer scale. Future research will focus on developing novel materials, investigating potential synthesis techniques, and improving existing high-energy raw materials. The endeavors aim is to enhance the efficiency of energy conversion, the absorption of radiation, and the coherence of physiochemical processes.

A critical review on metal-organic frameworks (MOFs) based nanomaterials for biomedical applications: Designing, recent trends, challenges, and prospects

Nanomaterials (NMs) have garnered significant attention in recent decades due to their versatile applications in a wide range of fields. Thanks to their tiny size, enhanced surface modifications, impressive volume-to-surface area ratio, magnetic properties, and customized optical dispersion. NMs experienced an incredible upsurge in biomedical applications including diagnostics, therapeutics, and drug delivery. This minireview will focus on notable examples of NMs that tackle important issues, demonstrating various aspects such as their design, synthesis, morphology, classification, and use in cutting-edge applications. Furthermore, we have classified and outlined the distinctive characteristics of the advanced NMs as nanoscale particles and hybrid NMs. Meanwhile, we emphasize the incredible potential of metal-organic frameworks (MOFs), a highly versatile group of NMs. These MOFs have gained recognition as promising candidates for a wide range of bio-applications, including bioimaging, biosensing, antiviral therapy, anticancer therapy, nanomedicines, theranostics, immunotherapy, photodynamic therapy, photothermal therapy, gene therapy, and drug delivery. Although advanced NMs have shown great potential in the biomedical field, their use in clinical applications is still limited by issues such as stability, cytotoxicity, biocompatibility, and health concerns. This review article provides a thorough analysis offering valuable insights for researchers investigating to explore new design, development, and expansion opportunities. Remarkably, we ponder the prospects of NMs and nanocomposites in conjunction with current technology.

In-situ formatting donor-acceptor polymer with giant dipole moment and ultrafast exciton separation

Donor-acceptor semiconducting polymers present countless opportunities for application in photocatalysis. Previous studies have showcased their advantages through direct bottom-up methods. Unfortunately, these approaches often involve harsh reaction conditions, overlooking the impact of uncontrolled polymerization degrees on photocatalysis. Besides, the mechanism behind the separation of electron-hole pairs (excitons) in donor-acceptor polymers remains elusive. This study presents a post-synthetic method involving the light-induced transformation of the building blocks of hyper-cross-linked polymers from donor-carbon-donor to donor-carbon-acceptor states, resulting in a polymer with a substantial intramolecular dipole moment. Thus, excitons are efficiently separated in the transformed polymer. The utility of this strategy is exemplified by the enhanced photocatalytic hydrogen peroxide synthesis. Encouragingly, our observations reveal the formation of intramolecular charge transfer states using time-resolved techniques, confirming transient exciton behavior involving separation and relaxation. This light-induced method not only guides the development of highly efficient donor-acceptor polymer photocatalysts but also applies to various fields, including organic solar cells, light-emitting diodes, and sensors.

Recent Updates on Multifunctional Nanomaterials as Antipathogens in Humans and Livestock: Classification, Application, Mode of Action, and Challenges

Pathogens cause infections and millions of deaths globally, while antipathogens are drugs or treatments designed to combat them. To date, multifunctional nanomaterials (NMs), such as organic, inorganic, and nanocomposites, have attracted significant attention by transforming antipathogen livelihoods. They are very small in size so can quickly pass through the walls of bacterial, fungal, or parasitic cells and viral particles to perform their antipathogenic activity. They are more reactive and have a high band gap, making them more effective than traditional medications. Moreover, due to some pathogen's resistance to currently available medications, the antipathogen performance of NMs is becoming crucial. Additionally, due to their prospective properties and administration methods, NMs are eventually chosen for cutting-edge applications and therapies, including drug administration and diagnostic tools for antipathogens. Herein, NMs have significant characteristics that can facilitate identifying and eliminating pathogens in real-time. This mini-review analyzes multifunctional NMs as antimicrobial tools and investigates their mode of action. We also discussed the challenges that need to be solved for the utilization of NMs as antipathogens.

Facile Construction of Intramolecular g-CN-PTCDA Donor-Acceptor System for Efficient CO2 Photoreduction

Due to the different electron affinity, the construction of a donor-acceptor (DA) system in the graphitic carbon nitride (g-CN) matrix is an attractive tactic to accelerate photo-induced electron-holes separation, and then further elevate its photocatalytic performance. In this work, perylene tetracarboxylic dianhydride (PTCDA) with magnificent electron affinity and excellent thermal stability was chosen to copolymerize with urea via facile one-pot thermal copolymerization to fabricate g-CN-PTCDA equipped with DA structures. The specific surface area of g-CN-PTCDA would be enlarged and the visible light absorption range would be broadened simultaneously when adopting this copolymerization strategy. A series of characterizations such as electron paramagnetic resonance (EPR), steady and transient photoluminescence spectra (PL), electrochemical impedance spectroscopy (EIS), and photocurrent tests combined with computational simulation confirmed the charge separation and transfer efficiency dramatically improved due to the DA structures construction. When 0.25% wt PTCDA was introduced, the CO evolution rate was nearly 23 times than that of pristine g-CN. The CO evolution rate could reach up to 87.2 μmol g−1 h−1 when certain Co2+ was added as co-catalytic centers. Meanwhile, g-CN-1 mg PTCDA-Co exhibited excellent long-term stability and recyclability as a heterogeneous photocatalyst. This research may shed light on designing more effective DA structures for solar-to-energy conversion by CO2 reduction.

Modulation of the Structure of the Conjugated Polymer TMP and the Effect of Its Structure on the Catalytic Performance of TMP-TiO2 under Visible Light: Catalyst Preparation, Performance and Mechanism

The photocatalytic activity of titanium dioxide (TiO₂) is largely hindered by its low photoresponse and quantum efficiency. TiO₂ modified by conjugated polymers (CPs) is considered a promising approach to enhance the visible light responsiveness of TiO₂. In this work, in order to investigate the effect of CP structural changes on the photocatalytic performance of TiO₂ under visible light, trimesoyl chloride-melamine polymers (TMPs) with different structural characteristics were created by varying the parameters of the polymerisation process of tricarbonyl chloride (TMC) and melamine (M). The TMPs were subsequently composited with TiO₂ to form complex materials (TMP-TiO₂) using an in situ hydrothermal technique. The photocatalytic activity of TMP-TiO₂ was evaluated by the degradation of rhodamine B (RhB). The results showed that the trend of the structure of the TMP with the reaction conditions was consistent with the visible light responsiveness of TMP-TiO₂, and TMP (1:1)-TiO₂ had the best photocatalytic activity and could degrade 96.1% of the RhB. In conclusion, our study provided new insights into the influence of the structural changes of TMPs on the photocatalytic activity of TMP-TiO₂ under visible light, and it improves our understanding of how conjugated polymers affect the photocatalytic activity of TiO₂ under visible light.

Recent Advances and Future Perspectives of Metal-Based Electrocatalysts for Overall Electrochemical Water Splitting

Recently, the growing demand for a renewable and sustainable fuel alternative is contingent on fuel cell technologies. Even though it is regarded as an environmentally sustainable method of generating fuel for immediate concerns, it must be enhanced to make it extraordinarily affordable, and environmentally sustainable. Hydrogen (H₂ ) synthesis by electrochemical water splitting (ECWS) is considered one of the foremost potential prospective methods for renewable energy output and H₂ society implementation. Existing massive H₂ output is mostly reliant on the steaming reformation of carbon fuels that yield CO₂ together with H₂ and is a finite resource. ECWS is a viable, efficient, and contamination-free method for H₂ evolution. Consequently, developing reliable and cost-effective technology for ECWS was a top priority for scientists around the globe. Utilizing renewable technologies to decrease total fuel utilization is crucial for H₂ evolution. Capturing and transforming the fuel from the ambient through various renewable solutions for water splitting (WS) could effectively reduce the need for additional electricity. ECWS is among the foremost potential prospective methods for renewable energy output and the achievement of a H₂ -based economy. For the overall water splitting (OWS), several transition-metal-based polyfunctional metal catalysts for both cathode and anode have been synthesized. Furthermore, the essential to the widespread adoption of such technology is the development of reduced-price, super functional electrocatalysts to substitute those, depending on metals. Many metal-premised electrocatalysts for both the anode and cathode have been designed for the WS process. The attributes of H₂ and oxygen (O₂ ) dynamics interactions on the electrodes of water electrolysis cells and the fundamental techniques for evaluating the achievement of electrocatalysts are outlined in this paper. Special emphasis is paid to their fabrication, electrocatalytic performance, durability, and measures for enhancing their efficiency. In addition, prospective ideas on metal-based WS electrocatalysts based on existing problems are presented. It is anticipated that this review will offer a straight direction toward the engineering and construction of novel polyfunctional electrocatalysts encompassing superior efficiency in a suitable WS technique.

A Targeted Review of Current Progress, Challenges and Future Perspective of g-C3 N4 based Hybrid Photocatalyst Toward Multidimensional Applications

The increasing demand for searching highly efficient and robust technologies in the context of sustainable energy production totally rely onto the cost-effective energy efficient production technologies. Solar power technology in this regard will perceived to be extensively employed in a variety of ways in the future ahead, in terms of the combustion of petroleum-based pollutants, CO₂ reduction, heterogeneous photocatalysis, as well as the formation of unlimited and sustainable hydrogen gas production. Semiconductor-based photocatalysis is regarded as potentially sustainable solution in this context. g-C₃ N₄ is classified as non-metallic semiconductor to overcome this energy demand and enviromental challenges, because of its superior electronic configuration, which has a median band energy of around 2.7 eV, strong photocatalytic stability, and higher light performance. The photocatalytic performance of g-C₃ N₄ is perceived to be inadequate, owing to its small surface area along with high rate of charge recombination. However, various synthetic strategies were applied in order to incorporate g-C₃ N₄ with different guest materials to increase photocatalytic performance. After these fabrication approaches, the photocatalytic activity was enhanced owing to generation of photoinduced electrons and holes, by improving light absorption ability, and boosting surface area, which provides more space for photocatalytic reaction. In this review, various metals, non-metals, metals oxide, sulfides, and ferrites have been integrated with g-C₃ N₄ to form mono, bimetallic, heterojunction, Z-scheme, and S-scheme-based materials for boosting performance. Also, different varieties of g-C₃ N₄ were utilized for different aspects of photocatalytic application i. e., water reduction, water oxidation, CO₂ reduction, and photodegradation of dye pollutants, etc. As a consequence, we have assembled a summary of the latest g-C₃ N₄ based materials, their uses in solar energy adaption, and proper management of the environment. This research will further well explain the detail of the mechanism of all these photocatalytic processes for the next steps, as well as the age number of new insights in order to overcome the current challenges.

A Comprehensive Review on Graphitic Carbon Nitride for Carbon Dioxide Photoreduction

Inspired by natural photosynthesis, harnessing the wide range of natural solar energy and utilizing appropriate semiconductor-based catalysts to convert carbon dioxide into beneficial energy species, for example, CO, CH₄ , HCOOH, and CH₃ COH have been shown to be a sustainable and more environmentally friendly approach. Graphitic carbon nitride (g-C₃ N₄ ) has been regarded as a highly effective photocatalyst for the CO₂ reduction reaction, owing to its cost-effectiveness, high thermal and chemical stability, visible light absorption capability, and low toxicity. However, weaker electrical conductivity, fast recombination rate, smaller visible light absorption window, and reduced surface area make this catalytic material unsuitable for commercial photocatalytic applications. Therefore, certain procedures, including elemental doping, structural modulation, functional group adjustment of g-C₃ N₄ , the addition of metal complex motif, and others, may be used to improve its photocatalytic activity towards effective CO₂ reduction. This review has investigated the scientific community's perspectives on synthetic pathways and material optimization approaches used to increase the selectivity and efficiency of the g-C₃ N₄ -based hybrid structures, as well as their benefits and drawbacks on photocatalytic CO₂ reduction. Finally, the review concludes a comparative discussion and presents a promising picture of the future scope of the improvements.

Recent Advancement in Rational Design Modulation of MXene: A Voyage from Environmental Remediation to Energy Conversion and Storage

Use of MXenes (Ti₃ C₂ T_x ), which belongs to the family of two-dimensional transition metal nitrides and carbides by encompassing unique combination of metallic conductivity and hydrophilicity, is receiving tremendous attention, since its discovery as energy material in 2011. Owing to its precursor selective chemical etching, and unique intrinsic characteristics, the MXene surface properties are further classified into highly chemically active compound, which further produced different surface functional groups i. e., oxygen, fluorine or hydroxyl groups. However, the role of surface functional groups doesn't not only have a significant impact onto its electrochemical and hydrophilic characteristics (i. e., ion adsorption/diffusion), but also imparting a noteworthy effect onto its conductivity, work function, electronic structure and properties. Henceforth, such kind of inherent chemical nature, robust electrochemistry and high hydrophilicity ultimately increasing the MXene application as a most propitious material for overall environment-remediation, electrocatalytic sensors, energy conversion and storage application. Moreover, it is well documented that the role of MXenes in all kinds of research fields is still on a progress stage for their further improvement, which is not sufficiently summarized in literature till now. The present review article is intended to critically discuss the different chemical aptitudes and the diversity of MXenes and its derivates (i. e., hybrid composites) in all aforesaid application with special emphasis onto the improvement of its surface characteristics for the multidimensional application. However, this review article is anticipated to endorse MXenes and its derivates hybrid configuration, which is discussed in detail for emerging environmental decontamination, electrochemical use, and pollutant detection via electrocatalytic sensors, photocatalysis, along with membrane distillation and the adsorption application. Finally, it is expected, that this review article will open up new window for the effective use of MXene in a broad range of environmental remediation, energy conversion and storage application as a novel, robust, multidimensional and more proficient materials.

Recent advancement in conjugated polymers based photocatalytic technology for air pollutants abatement: Cases of CO2, NOx, and VOCs

According to World Health Organization (WHO) survey, air pollution has become the major reason of several fatal diseases, which had led to the death of 7 million peoples around the globe. The 9 people out of 10 breathe air, which exceeds WHO recommendations. Several strategies are in practice to reduce the emission of pollutants into the air, and also strict industrial, scientific, and health recommendations to use sustainable green technologies to reduce the emission of contaminants into the air. Photocatalysis technology recently has been raised as a green technology to be in practice towards the removal of air pollutants. The scientific community has passed a long pathway to develop such technology from the material, and reactor points of view. Many classes of photoactive materials have been suggested to achieve such a target. In this context, the contribution of conjugated polymers (CPs), and their modification with some common inorganic semiconductors as novel photocatalysts, has never been addressed in literature till now for said application, and is critically evaluated in this review. As we know that CPs have unique characteristics compared to inorganic semiconductors, because of their conductivity, excellent light response, good sorption ability, better redox charge generation, and separation along with a delocalized π-electrons system. The advances in photocatalytic removal/reduction of three primary air-polluting compounds such as CO₂, NO_X, and VOCs using CPs based photocatalysts are discussed in detail. Furthermore, the synergetic effects, obtained in CPs after combining with inorganic semiconductors are also comprehensively summarized in this review. However, such a combined system, on to better charges generation and separation, may make the Adsorb & Shuttle process into action, wherein, CPs may play the sorbing area. And, we hope that, the critical discussion on the further enhancement of photoactivity and future recommendations will open the doors for up-to-date technology transfer in modern research.

NiFe2O4/g-C3N4 heterostructure with an enhanced ability for photocatalytic degradation of tetracycline hydrochloride and antibacterial performance

In this work, NiFe₂O₄/g-C₃N₄ heterostructure was prepared and used for the photocatalytic decomposition of tetracycline hydrochloride antibiotic and for inactivation of E. coli bacteria. The fabricated NiFe₂O₄/g-C₃N₄ composite displayed enhanced ability for photodegradation of organic pollutants and disinfection activities compared to the bare samples, because of the enhancement of visible light absorbance, heterojunction formation and photo-Fenton process. The optimized sample 10%-NiFe₂O₄/g-C₃N₄ has photodegraded 94.5% of tetracycline hydrochloride in 80 min. The active species trapping experiments revels that ·O₂^-, h⁺ and •OH are key decomposing species participated in the antibiotic degradation. It is hoped that the present study will provide a better understanding to fabricate efficient photocatalysts for the decomposition of organic pollutants and disinfection of bacteria.

Synergetic effect of bismuth vanadate over copolymerized carbon nitride composites for highly efficient photocatalytic H2 and O2 generation

The development of copolymerized carbon nitride (CN)-based photocatalysts may support advances in photocatalytic overall water splitting. However, the recombination of charge carriers is the main bottleneck that reduces its overall photocatalytic activity. To overcome this problem, the construction of heterojunction technology has emerged as an effective approach to reduce the charge carrier recombination, thereby improving charge separation and transport efficiency. In this work, an innovative heterojunction was prepared between Quinolinic acid (QA) modified CN (CN-QA_x) and novel nanorod-shaped bismuth vanadate (BiVO₄) (BiVO₄/CN-QA_x) for overall water splitting through a simple in-situ solvent evaporation technique. The obtained results show that the synthesized samples have efficient and improved activities for releasing H₂ (862.1 μmol/h) and O₂ (31.58 μmol/h) under visible light irradiation. Furthermore, an exceptional apparent quantum yield (AQY) of 64.52 % has been recorded for BiVO₄/CN-QA_7.0 at 420 nm, which might be due to the substantial isolation of photoinducedcharge carriers. Therefore, this work opens up a new channel toward efficient CN-based photocatalysts in the sustainable energy production processes.

Recent Advancement of the Current Aspects of g-C3 N4 for its Photocatalytic Applications in Sustainable Energy System

Being one of the foremost enticing and intriguing innovations, heterogeneous photocatalysis has also been used to effectively gather, transform, and conserve sustainable sun's radiation for the production of efficient and clean fossil energy as well as a wide range of ecological implications. The generation of solar fuel-based water splitting and CO₂ photoreduction is excellent for generating alternative resources and reducing global warming. Developing an inexpensive photocatalyst can effectively split water into hydrogen (H₂ ), oxygen (O₂ ) sources, and carbon dioxide (CO₂ ) into fuel sources, which is a crucial problem in photocatalysis. The metal-free g-C₃ N₄ photocatalyst has a high solar fuel generation potential. This review covers the most recent advancements in g-C₃ N₄ preparation, including innovative design concepts and new synthesis methods, and novel ideas for expanding the light absorption of pure g-C₃ N₄ for photocatalytic application. Similarly, the main issue concerning research and prospects in photocatalysts based g-C₃ N₄ was also discussed. The current dissertation provides an overview of comprehensive understanding of the exploitation of the extraordinary systemic and characteristics, as well as the fabrication processes and uses of g-C₃ N₄ .

Singh A, Singh AK, Singh AK, Baeg JO, Gupta SK. Design of a graphitic carbon nitride catalytic–biocatalytic system for solar light-based CO2 production

We report that generating (formic acid) and regenerating (NADH/NADPH) from CO2 and NAD+/NADP+ using a nitrogen-rich polymeric carbon nitride catalytic–biocatalytic system under solar light (λ > 420 nm) could provide a new approach for storage of clean energy.

Photocatalytic Removal of Antibiotics on g-C3N4 Using Amorphous CuO as Cocatalysts

Amorphous CuO is considered as an excellent cocatalyst, owing to its large surface area and superior conductivity compared with its crystalline counterpart. The current work demonstrates a facile method to prepare amorphous CuO, which is grown on the surface of graphitic carbon nitride (g-C3N4) and is then applied for the photocatalytic degradation of tetracycline hydrochloride. The prepared CuO/g-C3N4 composite shows higher photocatalytic activities compared with bare g-C3N4. Efficient charge transfer between g-C3N4 and CuO is confirmed by the photocurrent response spectra and photoluminescence spectra. This work provides a facile approach to prepare low-cost composites for the photocatalytic degradation of antibiotics to safeguard the environment.

Nanostructure Engineering via Intramolecular Construction of Carbon Nitride as Efficient Photocatalyst for CO2 Reduction

Light-driven heterogeneous photocatalysis has gained great significance for generating solar fuel; the challenging charge separation process and sluggish surface catalytic reactions significantly restrict the progress of solar energy conversion using a semiconductor photocatalyst. Herein, we propose a novel and feasible strategy to incorporate dihydroxy benzene (DHB) as a conjugated monomer within the framework of urea containing CN (CNU-DHBx) to tune the electronic conductivity and charge separation due to the aromaticity of the benzene ring, which acts as an electron-donating species. Systematic characterizations such as SPV, PL, XPS, DRS, and TRPL demonstrated that the incorporation of the DHB monomer greatly enhanced the photocatalytic CO₂ reduction of CN due to the enhanced charge separation and modulation of the ionic mobility. The significantly enhanced photocatalytic activity of CNU–DHB_15.0 in comparison with parental CN was 85 µmol/h for CO and 19.92 µmol/h of the H₂ source. It can be attributed to the electron–hole pair separation and enhance the optical adsorption due to the presence of DHB. Furthermore, this remarkable modification affected the chemical composition, bandgap, and surface area, encouraging the controlled detachment of light-produced photons and making it the ideal choice for CO₂ photoreduction. Our research findings potentially offer a solution for tuning complex charge separation and catalytic reactions in photocatalysis that could practically lead to the generation of artificial photocatalysts for efficient solar energy into chemical energy conversion.

A Superficial Intramolecular Alignment of Carbon Nitride through Conjugated Monomer for Optimized Photocatalytic CO2 Reduction

One of the most frequent ways to widen the adsorption range of carbon nitride (CN) is to add a well-known photosensitizer into its basic structure. So far, such attachments have been accomplished by using weak van der Waals forces. However, using strong covalent bonding to attach such photosensitizer with CN is yet to be determined. Here, for the first time, we covalently bonded porphyrin (5,10,15,20-tetrakis(4-(2,4-diamino-1,3,5-triazinyl) phenyl)-Porphyrin (TDP)), a renowned photosensitizer, effectively with CN by thermally balanced molecular strategy. A photoreaction system was set up for the deoxygenated conversion of CO2 to CO under visible light, where cobalt acted as a redox controller to speed up the charge transportation, while CN-TDP worked as a CO2 activating photocatalyst. The subsequent photocatalyst has a broader absorbance range, a greater specific surface area, and intramolecular organic connections that help to decrease the electron-hole pairs’ recombination rate. Furthermore, the average weight ratio between urea and TDP was well-tuned, resulting in a fantastic CO2 photoconversion for CN-TDP7.0 compared to the blank sample. This substantial increase in photocatalytic activity predicts a significant shift in CN’s specific surface area, band gap, chemical composition, and structure, as well as the efficient separation of photogenerated charge carriers from the ground state (HOMO) to the excited state (LUMO), making it a top candidate for CO2 photoreduction. At the same time, this approach paves the path for the bottom-up fabrication of carbon nitride nanosheets.

Bismuth-Graphene Nanohybrids: Synthesis, Reaction Mechanisms, and Photocatalytic Applications—A Review

Photocatalysis is a classical solution to energy conversion and environmental pollution control problems. In photocatalysis, the development and exploration of new visible light catalysts and their synthesis and modification strategies are crucial. It is also essential to understand the mechanism of these reactions in the various reaction media. Recently, bismuth and graphene’s unique geometrical and electronic properties have attracted considerable attention in photocatalysis. This review summarizes bismuth-graphene nanohybrids’ synthetic processes with various design considerations, fundamental mechanisms of action, heterogeneous photocatalysis, benefits, and challenges. Some key applications in energy conversion and environmental pollution control are discussed, such as CO2 reduction, water splitting, pollutant degradation, disinfection, and organic transformations. The detailed perspective of bismuth-graphene nanohybrids’ applications in various research fields presented herein should be of equal interest to academic and industrial scientists.

Molecular engineering of carbon nitride towards photocatalytic H2 evolution and dye degradation

The development of superior heterogeneous catalyst for hydrogen (H₂) evolution is a significant feature and challenging for determining the energy and environmental crises. However, the dumping of numerous lethal colorants (dye) as of textile manufacturing has fascinated widespread devotion-aimed water pollution anticipation and treatment. In this regard, a photocatalytic H₂ evolution by visible light using low-dimensional semiconducting materials having pollutant degradable capacity for Rhodamine B dyes (RhB) has been anticipated as a route towards environmental aspect. Here we fabricated the incorporation of organic electron-rich heterocyclic monomer 2,6-dimethylmorpholine (MP), inside electron-poor graphitic carbon nitride (g-CN) semiconductor by solid-state co-polymerization. The supremacy of copolymerization process was successfully examined via absorbent, calculated band gap, and migration of electrons on the photocatalytic performance of as-constructed CN-MP copolymer. The density functional theory (DFT) calculation provides extra support as evident for the successful integration of MP into the g-CN framework by this means-reduced band gap upon co-polymerization. The hydrogen evolution rate (HER) for g-CN was found as 115.2 μmol/h, whereas for CN-PM_0.1was estimated at 641.2 μmol/h (six times higher). In particular, the pseudo-order kinetic constant of CN-MP_0.1 for photodegradation of RhB was two times higher than that ofg-CN. Results show an important step toward tailor-designed and explain the vital role of the D-A system for the rational motifs of productive photocatalysts with effective pollutant degradable capability for future demand.

NiP/CuO composites: Electroless plating synthesis, antibiotic photodegradation and antibacterial properties

This work reports a simple method to prepare nickel-phosphorus (Ni-P) alloy modified CuO (Ni-P/CuO) composite, which shows excellent performance in terms of photodegradation antibiotics, particularly regarding the antibacterial properties. The Ni-P/CuO composites were prepared via two steps. The first step was to produce CuO by the hydrothermal method and the second step was to grow Ni-P in-situ on the surface of CuO through electroless plating. After loading of Ni-P, the photocatalytic activity of CuO for the decomposition of antibiotics is significantly increased under visible light irradiation. The photocatalytic activity of Ni-P/CuO with 4 wt% Ni-P loading is 25 times higher than that of CuO. Compared with CuO, the antibacterial activity of Ni-P/CuO with 4 wt% Ni-P loading against Escherichia coli is strongly increased. Based on the photoluminescence and photocurrent measurements of CuO and Ni-P/CuO, Ni-P cocatalyst improves the separation and transfer of the photogenerated charge in CuO, and enhances the photocatalytic activity of antibacterial performance. This work reveals that using Ni-P as the cocatalyst can strengthen the photocatalytic performance of CuO, which has great application potential in water purification and antibacterial treatments.

Synthesis of a new zinc phthalocyanine–benzoquinone rigid dyad

A new zinc phthalocyanine–benzoquinone rigid dyad, QnZnPc–G[Formula: see text] was synthesized as a model compound to study photo-induced charge separation mimicking natural photosynthesis. Compared to its previously reported analog, this dyad has an additional fused benzene ring between the zinc phthalocyanine (ZnPc) (donor) and benzoquinone (acceptor) moieties. The rigid structure of QnZnPc–G[Formula: see text] ([Formula: see text] no rotamers) is designed to minimize the unusual electronic perturbation induced by the internal motions, which resulted in a significant increase in the lifetime of the charged separated state (from 40 ps to 252 ps). Physical and photochemical properties of this new dyad were examined and discussed in this paper.

Probing the physio-chemical appraisal of green synthesized PbO nanoparticles in PbO-PVC nanocomposite polymer membranes

Different plants can be used to prepare nanoparticles. This is termed as green technology. It is one of the best ecofriendly and low-cost method for the preparation of nanoparticles which has no harmful effects. PbO nanoparticles were prepared by green method using leaf extract of Datura Sternum plants. The preparation of Lead oxide was confirmed by color change from colorless to yellowish brown. UV-Visible peak obtained at 250 nm and XRD study clarified the formation of PbO NPs. These PbO nanoparticles were then applied for the preparation of Nano Composite Polymer Membranes (nCPMs). PbO-PVC nCPMs were prepared based on polyvinyl chloride (PVC) polymer and PbO filler with the help of solution casting method, using cyclohexanone as a solvent. Different percentage (5-35%) of filler was used. The physiochemical parameters studied were viscosity, water uptake (WU), perpendicular swelling (DT) in deionized water, density, porosity (ε), morphology, ion adsorption capacity (IAC) and electrical conductivity (σ). The values of all these parameters except viscosity and conductivity were increased on increasing filler percentage. Viscosity of the nCPMs solution was decreased from 171 to 46.21. The conductivity of nCPMs was first increased upto 25% filler and then decreased. The deformation in PVC structure was increased on enhancing PbO amount. The values of Density, porosity, water uptake, DT and IAC were found in range 1.15-5.02, 0.50-0.87, 72.01-141.30, 0.012-0.11, and 3.13 × 10⁷-8.60 × 10⁷ respectively.

Construction of 1D Ag-AgBr/AlOOH Plasmonic Photocatalyst for Degradation of Tetracycline Hydrochloride

In this work, the highly efficient and low-cost Ag-AgBr/AlOOH plasmonic photocatalyst is successfully prepared via a simple and mild wet-chemical process and used for degrading high concentration methylene blue (MB) and tetracycline hydrochloride (TCH). The optimized 6-Ag-AgBr/AlOOH sample showed a 79% decomposition of TCH in 2 h, which is almost two times higher than that of bare AgBr (37%). For degrading MB, the photocatalytic activity of 6-Ag-AgBr/AlOOH (decomposing 84% in 2 h) showed a large enhancement as compared to bare AgBr (only 57%). The TEM, HRTEM, XRD, DRS, and XPS characterization results confirm that Ag-AgBr is a composite catalyst formed by loading Ag nanoparticles onto AgBr surfaces and then loaded on to AlOOH. The possible mechanism proposed is that •O 2 - and •OH radicals produced under sun light are the main active species for degrading MB and TCH. It is hoped that this work will open a new gateway to the synthesis of highly efficient and low-cost Ag-AgBr/AlOOH plasmonic photocatalysts for degrading organic pollutants.

Constructing Hierarchical Porous Carbons With Interconnected Micro-mesopores for Enhanced CO2 Adsorption

A high cost-performance carbon dioxide sorbent based on hierarchical porous carbons (HPCs) was easily prepared by carbonization of raw sugar using commercially available nano-CaCO3 as a double-acting template. The effects of the initial composition and carbonization temperature on the micro-mesoporous structure and adsorption performance were examined. Also, the importance of post-activation behavior in the development of micropores and synthesis route for the formation of the interconnected micro-mesoporous structure were investigated. The results revealed excellent carbon dioxide uptake reaching up 2.84 mmol/g (25oC, 1 bar), with micropore surface area of 786 m2/g, micropore volume of 0.320 cm3/g and mesopore volume of 0.233 cm3/g. We found that high carbon dioxide uptake was ascribed to the developed micropores and interconnected micro-mesoporous structure. As an expectation, the optimized HPCs offers a promising new support for the high selective capture of carbon dioxide in the future.

Rational Ionothermal Copolymerization of TCNQ with PCN Semiconductor for Enhanced Photocatalytic Full Water Splitting

Photocatalytic full water splitting remains the perfect way to generate oxygen (O₂) and hydrogen (H₂) gases driven by sunlight to address the future environmental issues as well as energy demands. Owing to its exceptional properties, polymeric carbon nitride (PCN) has been one of the most widely investigated semiconductor photocatalysts. Nevertheless, blank PCN characteristically displays restrained photocatalytic performance due to high-density defects in its framework that may perhaps perform the part of the recombination midpoint for photoproduced electron-hole pairs. Therefore, to overcome this problem, a simple approach to introduce 7,7,8,8-tetracyanoquinodimethane (TCNQ) with an electron-withdrawing characteristic modifier into the pristine PCN framework by the ionothermal method to enhance its optical, conductive, and photocatalytic properties has been undertaken. Results show that such integration of TCNQ results in the delocalization of the π-conjugated structure; significant changes in its chemical electronic configuration, band gap, and surface area; and enhanced production of electrons under visible light. As a result of this facile integration, our best sample (CNU-TCNQ_9.0) produced a hydrogen evolution rate (HER) of 164.6 μmol h^-1 for H₂ and an oxygen evolution rate (OER) of 14.8 μmol h^-1 for O₂, which were found to be 2.4- and 2.6-fold greater than those produced with pure carbon nitride (CNU) sample, respectively. Hence, this work provides a reasonable alternative method to synthesize and design novel CNU-TCNQ backbone photocatalyst for organic photosynthesis, CO₂ reduction, hydrogen evolution, etc.