Nitrogen Fixation Performance Research Articles

Synthesis and photocatalytic properties of polyaniline modified cadmium-manganese sulfide materials

In the present paper, polyaniline modification of Mn0.5Cd0.5S composite (PANI/MCS) was fabricated by a simple electrostatic adsorption method. The introduction of PANI makes PANI/MCS composites have better visible light absorption and higher photogenerated carrier segregation efficiency, thus showing better photocatalytic performance. The results show that the 50-PANI/MCS photocatalyst has the best hydrogen production capacity, which was 2.2 times greater than neat MCS. Meanwhile, the nitrogen fixation performance of the best sample 50-PANI/MCS was 4.93 times that of pure MCS. After that, a reasonable reaction mechanism was obtained through various characterization data. A cheap and readily available composite photocatalyst has been synthesized. This paper has good reference value in the area of development of efficient composite photocatalyst.

Synthesis of VO‐TiO2/VC‐g‐C3N4 Heterojunction for Improving the Photocatalytic Activity by Introducing Defect Sites

AbstractDefect engineering is a proven strategy for enhancing the performance of photocatalysts. Herein, we present a new method for preparing heterojunction photocatalytic materials, VO‐TiO2/VC‐g‐C3N4, with enhanced activity. The presence of defect sites and a heterojunction structure in the catalyst gives rise to exceptional charge separation efficiency and light absorption capabilities. The synergistic effect of the heterojunction interface and activated defect sites, which act as active sites, significantly enhanced the overall photocatalytic performance of VO‐TiO2/VC‐g‐C3N4. The catalyst VO‐TiO2/VC‐g‐C3N4 exhibits superior photocatalytic activity in the NO degradation reaction: displaying 3.5‐ and 2.2 times higher degradation efficiency than VO‐TiO2 and VC‐g‐C3N4, respectively. Moreover, the nitrogen fixation performance of VO‐TiO2/VC‐g‐C3N4 is 3.8‐ and 3.1 times higher than that of VO‐TiO2 and VC‐g‐C3N4, respectively. Electron paramagnetic resonance (EPR) spectroscopy capture experiments revealed that 1O2 and ⋅ OH are the primary active species in the photocatalytic reaction. The collaboration of carbon vacancy defects, oxygen vacancy defects, and the heterojunction structure created additional active sites for VO‐TiO2/VC‐g‐C3N4. The insights gained from this study offer valuable guidance for the efficient design and synthesis of VO‐TiO2/VC‐g‐C3N4 heterojunction photocatalysts, and lay a solid foundation for further research and development of such systems for large‐scale environmental remediation.

Experimental and theoretical study on potentiated photocatalytic nitrogen fixation of Mo doped InVO4 nanorods

Photocatalytic nitrogen fixation is acknowledged as an eco-friendly substitute for the conventional Haber-Bosch procedure for nitrogen (N2) conversion into ammonia (NH3). Localized electron-rich oxygen vacancies (OVs) on the surface of indium-based semiconductors have been proven to possess the capacity to capture and activate N2. Herein, oxygen vacancy-enriched Mo doped InVO4 nanorods with preferred orientation have been successfully synthesized via a simple hydrothermal reaction. Doping Mo into InVO4 nanorods can not only generate numerous OVs but also simultaneously modulate their electronic structure, significantly improving the efficiency of photocatalytic nitrogen fixation. Benefiting from the optimal Mo doped content, the 5 %Mo/InVO4 sample presents the optimal photocatalytic performance with the NH3 yield of 162.00 μmol·g−1·h−1, which is 2.4 times higher than that of pristine InVO4 sample. The characterization results reveal that the introduction of OVs augments light consumption and impedes the recombination of photogenerated electrons-hole pairs. Furthermore, the effect of OVs by doping Mo on the nitrogen fixation performance is also verified by the density functional theory (DFT) theoretical calculation. This work provides a new platform for the development of promising catalysts in the photocatalytic nitrogen fixation field, and has certain theoretical and practical value.

Construction of Fe(III) Active Sites on Phenanthroline-Grafted g-C3N4: Reduced Work Function and Enhanced Intramolecular Charge Transfer for Efficient N2 Photofixation.

Photocatalytic nitrogen fixation is one of the important pathways for green and sustainable ammonia synthesis, but the extremely high bonding energy of the N≡N triple bond makes it difficult for conventional nitrogen fixation photocatalysts to directly activate and hydrogenate. Given this, we covalently grafted the phenanthroline unit onto graphitic carbon nitride nanosheets (CN) by the simple thermal oxidation method and complexed it with transition metal Fe3+ ions to obtain stable dispersed Fe active sites, which can significantly improve the photocatalytic activity. The Fe(III)-4-P-CN photocatalyst morphology consists of porous lamellar structures internally connected by nanowires. The special morphology of the catalysts gives them excellent nitrogen fixation performance, with an average NH3 yield of 492.9 μmol g-1 h-1, which is 6.5 times higher than that of the pristine CN, as well as better photocatalytic cycling stability. Comprehensive experiments and density-functional theory results show that Fe(III)-4-P-CN is more favorable than pristine CN for *N2 activation, effectively lowering the reaction energy barrier. Moreover, other byproducts (such as nitrate and H2O2) are also produced during the photocatalytic nitrogen fixation process, which also provides a new way for nitrogen-fixing photocatalysts to achieve multifunctional applications.

Modulation of cationic vacancies in Co3O4 for promoted photocatalytic nitrogen fixation and electrocatalytic nitrate reduction to ammonia

Defect engineering offers a powerful approach to tune the local surface microstructure, electron band structure and chemistry of photo- and electro-catalysts, to thereby enhancing their performance in nitrogen reduction reaction (NRR) and electrocatalytic nitrate reduction to ammonia (NO3-RR). The present study has successfully synthesized cobalt-rich vacancy (VCo) Co3O4 through a two-step method, allowing for controlled manipulation of the concentration of cobalt vacancies through heat treatment. The impact of varying concentrations of cobalt vacancies on the performance of photocatalytic nitrogen reduction reaction and electrocatalytic nitrate ammonia production was investigated. Remarkably, the catalysts heat-treated at 500 °C, exhibited a significantly enhanced photocatalytic nitrogen fixation performance with a rate of 67.5 μmol·g-1·h-1. The catalysts heat-treated at 300 °C, exhibited an ammonia yield of 339.05 mmol·g-1·h-1 at -1.1 V (vs. RHE), while achieving a maximum Faraday efficiency of 84.3 % at -0.9 V (vs. RHE). The enhanced activity can be attributed to the presence of cobalt vacancies, which synergistically modulate both the structural and electronic properties. This dual functionality of cobalt-rich vacancy Co3O4 not only underscores its potential as a highly efficient photocatalyst for NRR and an electrocatalyst for NO3-RR but also highlights the intricate interplay between defect engineering, microstructural tuning, and electronic structure in promoting diverse catalytic activities. Our findings not only advance the fundamental understanding of defect-induced enhancements but also pave the way for the rational design of multifunctional catalysts capable of excelling in both photo- and electro-catalytic applications.

Synergistic effects of MoFe bimetallic carbon dots for enhanced photocatalytic nitrogen fixation

The fixation of nitrogen to ammonia by photocatalysis displays great prospects. To this end, designing efficient catalysts is vital. As a type of graphitic carbon nitride, g-C3N5 is rich in N atoms, which endows it with a superior energy band structure. To compensate for the lack of active sites and the fast recombination of photogenerated carriers, we constructed MoFe bimetallic carbon dots loaded g-C3N5, with an NH3 yield of 812.9 μmol h−1 gcat−1. The introduction of metal carbon dots facilitates charge transfer. Through further study, it was found that Fe sites are mainly responsible for activating nitrogen, while Mo sites tend to split water to produce protons. Bimetallic carbon dots showed a synergistic effect on the enhancement of nitrogen fixation performance. This work offers some insights for the construction of efficient nitrogen fixation catalysts with novel carbon dots types of active centers.

General corrosion endowed by electrolyte engineering enhancing Lithium-Mediated nitrogen fixation

Lithium-mediated ammonia electrochemical synthesis (LMAES) holds promise for approximating and superseding the capacity of Haber-Bosch technology. However, currently used tetrahydrofuran electrolyte in such system hinders the further enhancement of nitrogen fixation performance greatly due to the over-passivation of the reaction interface suppressing the corrosion rate of the active species on metallic lithium. Here, we develop a remarkably 1,2-diethoxyethane (DEE) electrolyte to enhance the performance of LMAES. Systematic simulations combined with experimental results jointly elucidate that the unique Li+ solvation environment in DEE electrolyte significantly weakens the passivation of the electrode interface and triggers the general corrosion behavior of active species to electrodeposited lithium. Compared with conventional tetrahydrofuran electrolyte, this DEE electrolyte brings nearly twice the improvement of Faradaic efficiency (from 33.4 % to 61.7 %). This work offers a progressive insight into advanced electrolyte designs for LMAES.

Directional design of the pyridine ligand functional block fine-tuned hydrophobicity to improve the electrocatalytic nitrogen fixation performance of the Co/Ni based MOFs-derived materials

A series of isostructural Co/Ni-MOFs with different linearly bridged bipyridines as organic linkers has been designed and synthesized. Experimental studies reveal that linker engineering by tuning the functional block of the pyridine-bridging units renders these MOFs derived materials with significantly improved electrocatalytic nitrogen reduction reactions (eNRR) to NH3. Among them, at −0.4 V vs reversible hydrogen electrode the one containing a 1,3,4-thiadiazole unit exhibits the best eNRR performance in 0.1 M Na2SO4 with the highest NH3 yield (39.7 μg h−1 mg−1) and Faraday efficiency (33.3 %). This excellent nitrogen fixation performance comes from the synergistic effect of the heterojunction formed by the Co2N component that is conducive to nitrogen fixation and the Co9S8 component that inhibits hydrogen evolution in the derived material. Significantly, the systematic tuning of the bridging ligands in MOFs provides a new pathway to develop eNRR electrocatalysts.

Effective 1D/2D nanostructured S-scheme W18O49/g-C3N4 heterojunction photocatalyst fabrication for improved photocatalytic nitrogen fixation performance

The fundamental insights into the reaction mechanism, especially the electron transfer mechanism, are highly promising yet challenging for W18O49/g-C3N4 heterojunction catalysts during photocatalytic nitrogen fixation. Herein, the 1D/2D nanostructured S-scheme heterojunctions were designed by in situ growth of 1D W18O49 nanowires on 2D g-C3N4 nanosheets through solvothermal method using methanol as solvent. In situ XPS analysis revealed that electrons in the conduction band of W18O49 recombine with holes in the valence band of g-C3N4 under the conduction effect of internal electric field, band bending, and Coulombic attraction in the W18O49/g-C3N4 heterojunction. The photogenerated electrons are retained in g-C3N4, where the negative reduction potential of its conduction band enhances the activation of N2. As a result, the ammonia generation rate employing the optimal W18O49/g-C3N4 heterojunction is 64.8 μmol gcat−1 h−1, approximately double that of W18O49 alone and 2.3 times higher than that of g-C3N4. The enhanced activity and facile methodology make the current material exceedingly appealing for implementation in photocatalytic nitrogen fixation for the synthesis of ammonia.

Enhanced photocatalytic nitrogen fixation performance via in situ constructing BiO2–x/NaNbO3 heterojunction

The fabrication of heterojunction catalysts is an effective strategy to enhance charge separation efficiency, thereby boosting the performance of photocatalysts. In this study, BiO2–x nanosheets were synthesized through a hydrothermal process and loaded onto NaNbO3 microcube to construct a series of BiO2–x/NaNbO3 heterojunctions for photocatalytic N2 fixation. Results indicated that 2.5% BiO2–x/NaNbO3 had the highest photocatalytic performance. The NH3 production rate under simulated solar light reached 406.4 μmol·L−1·g−1·h−1, which reaches 2.6 and 3.8 times that of NaNbO3 and BiO2–x, respectively. BiO2–x nanosheets primarily act as electron trappers to enhance the separation efficiency of charge carriers. The strong interaction between BiO2–x and NaNbO3 facilitate the electron migration between them. Meanwhile, the abundant oxygen vacancies in BiO2–x nanosheets may facilitate the adsorption and activation of N2, which may be another possible reason of the high photocatalytic activity of the BiO2–x/NaNbO3. This study may offer new insights for the development of semiconductor materials in photocatalytic nitrogen fixation.

Methane sulfonic acid-assisted synthesis of g-C3N4/Ni2P/Ni foam: Efficient, stable and recyclable for photocatalytic nitrogen fixation under visible light

Photocatalytic nitrogen fixation is of great significance for solving the energy crisis and healthy development of the environment. However, photocatalysts have problems such as low activity, poor stability and difficult recovery, which seriously limit their application. Herein, we in situ synthesized g-C3N4/Ni2P/Ni three-dimensional reticulated foam photocatalysts (CNNPF) with excellent photocatalytic nitrogen fixation performance under visible light by a two-step methane sulfonic acid-assisted carbon nitride loading-calcined phosphatisation method, using nickel foam as the carrier and raw material. The results showed that the CNNPF had a stable three-dimensional network structure, and g-C3N4 was stably immobilized to the nickel foam skeleton with Ni2P. The best performance of CNNPF with ultrasonication for 2 h and phosphatisation for 1 h showed a high photocatalytic nitrogen fixation efficiency of up to 373 μmol·h−1·g−1, which was attributed to the Ni2P co-catalyst modification of g-C3N4 that led to the improvement of photogenerated electron-hole pair separation efficiency. Meanwhile, the three-dimensional network structure is favorable to provide more active sites for N2 adsorption and activation. In addition, the prepared material also has good stability and recyclability, and its nitrogen fixation efficiency was still maintained at 350 μmol·h−1·g−1 after five cycles. The present work provides a direction for the design of efficient and recyclable photocatalytic systems that show great potential in the field of economically sustainable nitrogen fixation.

In-MOF derived In2S3-X@ZnS heterojunction with rich sulfur vacancies for enhanced performance in photocatalytic nitrogen fixation

Photocatalytic nitrogen fixation has the characteristics of green, energy-saving and environment-friendly. Herein, the hollow microtube-flower In2S3-X@ZnS with rich sulfur vacancies was synthesized by the one-step solvothermal method of sulfurization from the precursor MIL-68(In). In-MOF derived sulfur-vacancy modulation and the construction of the In2S3-X@ZnS heterojunction had been proved to be the desirable strategies to dramatically enhance the ammonia production rate. One the one hand, the characterizations of HRTEM, ESR and the transient photocurrent responses (TPR) in N2, Air and Ar saturated solution directly and indirectly proved the existence of rich sulfur-vacancy, which could be the active sites for the chemisorption and activation of N2. On the other hand, the results of EIS, PL and band analysis demonstrated that the established Type-п heterojunction promoted the photogenerated carriers to separate and clarified the enhanced photocatalytic mechanism, the corresponding nitrogen fixation performance had been greatly improved with a high yield rate of 58.988 µmol∙gcat−1∙h−1, which was evidently much higher than that of pristine In2S3-X and pure ZnS. This work provided a new insight for developing functional photocatalysts with the synergy effect of sulfur-vacancy and heterojunction for highly efficient nitrogen fixation.

Construction of a direct Z-scheme Mn0.5Cd0.5S/CoTiO3 heterojunction with enhanced photocatalytic nitrogen fixation performance

The exploration and design of highly efficient and robust photocatalysts composed of earth-abundant materials for ambient photocatalytic N2 fixation to ammonia remains a significant challenge. Here, we have fabricated a stable and highly efficient direct Z-scheme Mn0.5Cd0.5S/CoTiO3 heterostructure for N2 fixation by depositing Mn0.5Cd0.5S nanoparticles on CoTiO3 surface. Under ambient conditions, the optimized Mn0.5Cd0.5S/CoTiO3 heterojunction achieved a significant NH3 production rate of 121.9 μmol g-1h−1 without cocatalyst modification, representing a 5.1- and 5.9-fold increase over pristine Mn0.5Cd0.5S and CoTiO3, respectively, and also exceeding most previously reported photocatalytic systems. The significant improvement in ammonia production primarily results from the Z-scheme charge transfer path between the Mn0.5Cd0.5S and CoTiO3 components, which enables effective separation of photoinduced carriers while maintaining their robust redox capacity, thus dramatically boosting ammonia generation performance. This research may provide new insights for advancing other alternative Z-scheme photocatalytic systems with remarkable stability and exceptional efficiency in N2 fixation.

Cu-modified InVO4 photocatalysts for enhanced N2 fixation using chemical reagents and electroplating sludge as the Cu source.

Inspired by simulation analysis, we found that Cu decoration could enhance the NH3 production rate of InVO4 through promoting N2 adsorption and reducing the activation energy of the key hydrogenation step. 5% Cu/InVO4 exhibited an optimal NH3 yield of 195.11 μmol gcat-1 h-1, approximately six times higher than that of InVO4. Cu/InVO4 was also fabricated by upcycling Cu from electroplating sludge, achieving a gratifying nitrogen fixation performance of 154.13 μmol gcat-1 h-1.

Organik ve kimyasal gübre ile kullanılmak üzere mikroorganizma izolasyon ve karakterizasyonu

Isolation and Characterization of Microorganisms for Use with Manure and Chemical Fertilizers
 Levent Değirmenci1, Özge Kaygusuz İzgördü2, Cihan Darcan3
 ORCID: 0000-0001-6608-0398; 0000-0002-3652-4266; 0000-0003-0205-3774
 1 Corresponding author: Department of Chemical Engineering, Bilecik Şeyh Edebali University, 11210, Bilecik/Turkey Tel: +90 228 2141548, e-mail: levent.degirmenci@bilecik.edu.tr 
 2 Biotechnology Application and Research Center, Bilecik Şeyh Edebali University, 11210, Bilecik, Turkey 3 3Department of Molecular Biology and Genetics, Bilecik Şeyh Edebali University, 11210, Bilecik, Turkey
 
 Abstract
 A microbial consortium with the ability to utilize nitrogen of certain chemical fertilizers were established via a series of tests. Results indicated four strains, 3 of which were identified as Bacillus cereus sp and an Alcaligenes faecalis sp. which was the only non-Bacillus member of the consortium. The members of the consortium showed no antagonistic activity against each other implying their successful utilization as components of a commercial fertilizer.
 Keywords: IAA, siderophore, Bacillus spp., nitrogen fixation, ammonia/nitrite oxidation, MALDI-TOF MS
 
 Organik ve Kimyasal Gübre ,le Kullanılmak Üzere Mikroorganizma İzolasyon ve Karakterizasyonu
 
 Özet 
 Farklı kimyasal gübrelerin içeriğinde yer alan azotu bitkinin kullanımına sunabilen mikroorganizma karışımı bir dizi testler sonucunda elde edilmiştir. Sonuçların değerlendirilmesiyle mikroorganizma karışımına üç Bacillus Cereus sp. suşu ile karışımın Bacillus sp. olmayan tek üyesi Alcaligenes faecalis sp. seçilmiştir. Mikroorganizma karışımında yer alan suşların birbirlerine karşı antagonistik etki göstermediği dolayısıyla karışımın mikrobiyal gübre olarak ticarileştirilmesinin mümkün olduğu da elde edilen sonuçlar arasındadır. 
 Anahtar Kelimeler: IAA, siderophore, Bacillus spp. azot fiksasyonu, amonyum/nitrit oksidasyonu, MALDI-TOF MS
 1. Introduction 
 Chemical fertilizer is gaining an increasing attention and its harmful effects on environment possesses a serious threat [2]. Heavy metal accumulation is another problem during utilization of chemical fertilizers [2].The variation of soil pH, another problem encountered due to excessive fertilizer utilization, has negative impact on phosphorus uptake [3]. Plant growth promoting bacteria when added to soil, operate via certain mechanisms facilitating acquisition of already existing resources in soil [4]. Siderophore producing bacteria also acts as biocontrol agent capable of decreasing phytopathogen population in the flora [4–7].
 Certain procedures were developed and/or modified in the present study to obtain a microbial consortium which would act as an enhancer during plant growth. 
 2. Materials and Method
 
 2.1. Semi-selective isolation procedure as starting-point
 
 Semi-selective isolation procedures were conducted according to [12]. 
 2.2. Standard tests applied to determine the potential of isolates as PGPB.
 
 Nitrogen fixation ability, IAA production, phosphate solubility siderophore production were conducted according to [13-18]. 
 2.3. Specified tests to determine nitrogen evaluation potential of PGP isolates
 
 Nitrogen evaluation potential was determined according to [19]. 
 2.4. Biochemical tests conducted to determine Bacillus sp. in accordance with MALDI-TOF MS analyses evaluated for validation. 
 
 Biochemical tests were evaluated based on positive results for both caseinase activity and starch hydrolysis [20-22].
 MALDI-TOF MS analyses applied for selected strains and an isolate with positive activity towards siderophore production.
 3. Results 
 IAA production, Nitrogen fixation performance, Ammonifier selection, phosphate solubility, siderophore production ability, urea degradation, ammonium oxidation and nitrite oxidation abilities of strains were evaluated to establish a microbial consortium. 
 4. Conclusion and discussion
 • Media selection could serve as a selection criterion to assemble a certain group of microorganisms.
 • Tests conducted for isolates could be diversified to establish a consortium with modified properties.
 • Test procedures could be modified to facilitate establishment of microbial consortium.
 • Strains with different properties could serve as members of consortium which was the case in our study. 
 • Identification in species level was possible to a certain extent. MALDI-TOF MS analysis presented a brief idea on strains and similar results would have been obtained in the case of applying its costlier alternatives. Hence a relatively simpler procedure is concluded to be better for initial investigation.
 • Evaluation of results led to investigation of certain prospects including determination of physicotolerant activity of strains and management of Fusarium wilt disease as the topics of future investigations.

Electronic structure regulation and built-in electric field synergistically strengthen photocatalytic nitrogen fixation performance on Ti-BiOBr/TiO2 heterostructure

Electronic structure regulation and built-in electric field synergistically strengthen photocatalytic nitrogen fixation performance on Ti-BiOBr/TiO2 heterostructure

Construct electron transport path through NH2-MIL-125 modified Fe-doped W18O49 nanowires to enhance photocatalytic nitrogen fixation performance

Ammonia has important application value in agriculture and industry as a raw material for producing nitrogen fertilizers and organic chemicals. The Haber-Bosch method is generally utilized to synthesize ammonia through N2 and H2 as raw materials in industry, but the process generates serious energy consumption and pollution. In the paper, a heterojunction catalyst is constructed that adopts NH2-MIL-125 and Fe-doped W18O49 (Fe-W18O49) for photocatalytic nitrogen fixation. Fe-W18O49 is a nanowire containing oxygen vacancies (OVs). OVs can provide active sites for the adsorption and activation of nitrogen gas. The 3D plate-like morphology of NH2-MIL-125 can observably reduce the occurrence of nanowires aggregation. This phenomenon can be attributed to NH2-MIL-125 playing a supporting role in the fixation of nanowires. New mesoporous are formed between NH2-MIL-125 and Fe-W18O49 in the constructed compound catalyst, which can realize efficient mass transfer between the inside and outside of the catalyst. EPR characterization discovers that Fe-W18O49/NH2-MIL-125 cannot produce •O2˗ and •OH radicals. The type II heterojunction forms between Fe-W18O49 and NH2-MIL-125. The heterojunction improves the carrier migration path, and the photocurrent intensity is significantly increased. Under simulated sunlight, Fe-W18O49/NH2-MIL-125–2 emerges the best catalytic performance with an ammonia formation rate of 128.2 µmol g−1 h−1. The yield of ammonia is boosted in comparing with NH2-MIL-125 (13 times) and Fe-W18O49 (1.7 times). After several cycles, Fe-W18O49/NH2-MIL-125 remain maintains good stability during the catalytic process. This paper provides a possibility for constructing low-cost heterojunction catalysts in the territory of photocatalytic nitrogen fixation.

Solar-driven nitrogen fixation with bio-inspired Mo/Sr-MOFs photocatalysts at ambient conditions

Photocatalytic reduction of nitrogen to ammonia has attracted much attention recently because ammonia stands out as one of the indispensable chemicals on a global scale. Herein, bio-inspired MOFs Mo-NTC and Sr-NTC were designed and synthesized by using Mo or Sr as metal nodes and 1,4,5,8-naphthalenetetracarboxylic acid (H4NTC) as ligands which has visible-light responsiveness. The best photocatalytic nitrogen fixation performance of Sr-NTC was about 143.10 μmol·g−1·h−1 which is higher than Mo-NTC (70.20 μmol·g−1·h−1). The ability of Sr-NTC to convert nitrogen to ammonia was verified by 15N2 isotope labeling experiment and in-situ FTIR measurement. Various characterization methods were employed to confirm the enhanced performance of photocatalytic nitrogen reduction. This work provides a new idea for applying metal Sr and Mo and organic ligand to construct photocatalysis to fix nitrogen driven by solar at ambient conditions.

Enhanced nitrogen photofixation performance of g-C3N4 nanosheets anchored with Bi2O2CO3 and Bi2O3 under simulated solar light

BackgroundPhotocatalytic nitrogen fixation process has been considered an eco-friendly technology. Among visible-light-triggered photocatalysts, g-C3N4 is an excellent choice, due to its some attractive features. Nonetheless, activity limiting factors for photocatalytic proficiency of g-C3N4 are small specific surface area, limited absorption of visible light, fast recombination of photogenerated charges, and poor carrier transportation. MethodsIn this study, we anchored Bi2O2CO3 and Bi2O3 nanoparticles over the nanosheets of g-C3N4 through a facile one-pot refluxing method. The resultant g-C3N4 nanosheet/Bi2O2CO3/Bi2O3 photocatalysts displayed superior photocatalytic nitrogen fixation performance compared to the components. FindingsThe amount of ammonia generation over the optimum nanocomposite was 4064 μmol L−1 g−1, which was 7.89 and 2.19 folds as large as the g-C3N4 and g-C3N4 nanosheet photocatalysts, respectively. The impact of reaction media, Ar atmosphere, solution pH, and electron and hole scavengers was examined on ammonia production to gain more insights into the nitrogen fixation process. Finally, a p-n-n heterojunction mechanism was suggested for the outstanding N2 photofixation reaction over the g-C3N4 nanosheet/Bi2O2CO3/Bi2O3 photocatalysts.

Oxygen vacancy and Z-scheme heterojunction cooperate to promote visible light nitrogen photofixation

The combination of defect engineering and heterojunction design is a viable method to achieve high efficiency photocatalytic nitrogen fixation. Oxygen vacancy engineered Fe2O3/CeO2 Z-scheme heterojunction was synthesized by thermal treatment with Ce-MOFs as precursor. Fe2O3/CeO2 with 30 wt% Fe2O3 exhibited the highest NH3 yield of 162 μmol·g−1·h−1 in water, about 2.5 and 4 times that of CeO2 and Fe2O3, respectively. The enhanced photocatalytic nitrogen fixation performance could be attributed to the synergistic effect of the oxygen vacancies and the Z-scheme heterojunction, which significantly inhibited the recombination of charge pairs, induced electron-directed transfer, and promoted better adsorption and activation of N2. This work provides a new perspective for developing high-efficient and low-cost nitrogen fixation catalysts.