Photocatalytic Reduction Of N2 Research Articles

Constructing S-scheme heterojunction Cs3Bi2Br9/BiOBr via in-situ partial conversion to boost photocatalytic N2 fixation

The judicious construction of interfaces with swift charge communication to enhance the utilization efficiency of photogenerated carriers is a viable strategy for boosting the photocatalytic performance of heterojunctions. Herein, an in-situ partial conversion strategy is reported for decorating lead-free halide perovskite Cs3Bi2Br9 nanocrystals onto BiOBr hollow nanotube, resulting in the formation of an S-scheme heterojunction Cs3Bi2Br9/BiOBr. This unique in-situ growth approach imparts a closely contacted interface to the Cs3Bi2Br9/BiOBr heterojunction, facilitating interfacial electron transfer and spatial charge separation compared to a counterpart (Cs3Bi2Br9:BiOBr) fabricated via traditional electrostatic self-assembly. Additionally, the establishment of an S-scheme charge transfer pathway preserves the robust redox capability of photogenerated carriers. Furthermore, the free electron transfer from Cs3Bi2Br9 to BiOBr promotes the activation of the NN bond and diminishes the energy barrier associated with the rate-determining step in the N2 reduction process. Consequently, the Cs3Bi2Br9/BiOBr heterojunction exhibits highly selective photocatalytic N2 reduction to NH3 (nearly 100 %) at a rate of 130 μmol g−1 h−1 under simulated sunlight (100 mW cm−2), surpassing BiOBr, Cs3Bi2Br9, and Cs3Bi2Br9:BiOBr by factors of 6, 4, and 2, respectively.

The interface electric field accelerated charge transfer kinetics of 1D/0D TiO2/Bi2Sn2O7 Z-scheme heterojunction with close contact interface significantly improves photothermal catalytic N2 reduction

The slow kinetics of charge transfer and weak redox ability hindered the practical application of photocatalytic N2 reduction. Therefore, in this article, Bi2Sn2O7 nanoparticles were grown in situ on the surface of TiO2 nanorods using a solvothermal method to form a 1D/0D TiO2/Bi2Sn2O7 (TBSO-15) Z-scheme heterojunction with a tight contact interface. The results of density functional theory calculations (DFT) and Kelvin probe force microscopy (KPFM) indicated that the difference in Fermi levels led to spontaneous rearrangement of charges at the heterojunction interface and the formation of a strong interfacial electric field (IEF). IEF provided a powerful driving force for the spatial separation of photogenerated charges, accelerating charge transfer dynamics. Secondly, the Z-scheme migration pathway of photo-generated charges between TiO2 and Bi2Sn2O7 enhanced the redox ability of TBSO-15 and formed a spatially separated redox center. In addition, molecular dynamics simulations (MD) showed that the photothermal effect significantly promoted the dynamic diffusion of N2 and H2O, accelerating the chemical reaction kinetics. Therefore, the synergistic effect of the two significantly improved the performance of Photothermal catalytic N2 reduction (PTC-NRR). After simulating solar irradiation for 2 h, the PTC-NRR performance of TBSO-15 achieved 327.25 μmoL·g−1 in pure water, which was 19.7 times that of TiO2 and 4.2 times that of Bi2Sn2O7, respectively. This study provides a reference for the synergistic effect of charge space transfer dynamics and photothermal effect to promote PTC-NRR.

Bimetallic Fe, Co-Modified TiO2 Derived from NH2-MIL-125(Ti) as an Efficient Photocatalyst for N2 Fixation

The conversion of nitrogen (N2) and water (H2O) into NH3 by photocatalysis under ambient conditions has been considered an environmentally friendly strategy. However, developing effective catalysts for N2 fixation is still challenging. Herein, we report a bimetallic JH Fe, Co/TiO2 derived from NH2-MIL-125(Ti) by the fast Joule heating (FJH) method for visible–light–driven catalytic N2 fixation. It was found that the photocatalytic N2 reduction efficiency of bimetallic FC@TiO2-JH was improved, enabling an NH3 yield rate of 110.14 µmol g−1 h−1 without any sacrificial agents. Furthermore, the rate was higher than those of Fe@TiO2-JH and Co@TiO2-JH, suggesting that the synergistic effect between Fe and Co broke the electronic equilibrium and increased the center of its d-band, enhancing electronic feedback to the antibonding π* orbitals of N2 while weakening the bonding energy of N≡N. Meanwhile, the rate was about 2.75 times higher than that of FC@TiO2-TF, which was calcined in a tube furnace. It is assumed that FJH might lead to the formation of lattice defects, leading to localized charge deficiency, enhanced carrier separation, and transport. Thus, doping of Fe and Co synergistically interacted with the defects produced from FJH, facilitating the photocatalytic reduction process. As detected, it had a greater ability to separate hole–electron pairs and transferred electrons to adsorbed N2 at faster rates. Our work demonstrates a prospective strategy for designing bimetallic catalysts derived from NH2-MIL-125(Ti) for N2 fixation.

Nanoporous Heterojunction Photocatalysts with Engineered Interfacial Sites for Efficient Photocatalytic Nitrogen Fixation.

Photocatalytic N2 reduction reaction (PNRR) offers a promising strategy for sustainable production of ammonia (NH3). However, the reported photocatalysts suffer from low efficiency with great room to improve regarding the charge carrier utilization and active site engineering. Herein, a porous and chemically bonded heterojunction photocatalyst is developed for efficient PNRR to NH3 production via hybridization of two semiconducting metal-organic frameworks (MOFs), MIL-125-NH2 (MIL=Material Institute Lavoisier) and Co-HHTP (HHTP=2,3,6,7,10,11-hexahydroxytripehenylene). Experimental and theoretical results demonstrate the formation of Ti-O-Co chemical bonds at the interface, which not only serve as atomic pathway for S-scheme charge transfer, but also provide electron-deficient Co centers for improving N2 chemisorption/activation capability and restricting competitive hydrogen evolution. Moreover, the nanoporous structure allows the transportation of reactants to the interfacial active sites at heterojunction, enabling the efficient utilization of charge carriers. Consequently, the rationally designed MOF-based heterojunction exhibits remarkable PNRR performance with an NH3 production rate of 2.1 mmol g-1 h-1, an apparent quantum yield (AQY) value of 16.2% at 365 nm and a solar-to-chemical conversion (SCC) efficiency of 0.28%, superior to most reported PNRR photocatalysts. Our work provides new insights into the design principles of high-performance photocatalysts.

Z-scheme metal organic framework/Ag@AgCl heterojunction photocatalysts with elevated photocatalytic N2 fixation activity

As one of the most consumed chemical reagents, ammonia (NH3) has a wide range of applications in many fields. The demand for ammonia may continue to increase with the advancement of technology and the acceleration of industrialization. The traditional high energy consumption and high pollution ammonia synthesis methods (Haber-Bosch) need to be optimized and improved to reduce environmental pollution and energy dependence. In this work, a series of Z-scheme NM/Ag@AgCl heterojunctions were prepared as catalysts for the research of photocatalytic nitrogen fixation. By in-situ photodeposition, Ag@AgCl was uniformly distributed on the NM surface, and the interfaces of different substances were tightly bonded. The SPR effect that generated by Ag nanoparticles significantly enhanced the light energy absorption performance of heterojunction materials. In the ESR spectra, the signal peak intensity of NM/Ag@AgCl was higher than that of NM under light condition. Constructing of heterojunction was beneficial to the formation of Ti3+. The strong built-in electric field among NM and AgCl promoted the generation of Z-scheme heterojunction. NM/Ag@AgCl had sufficient redox potential to overcome thermodynamic barriers and drive the catalytic reaction. Without adding any sacrificial reagent, the ammonia production of NM/Ag@AgCl-3 reached 76.7 µmol g−1 h−1 under full spectrum radiation. The rate of ammonia formation of NM/Ag@AgCl was almost seven times than that of NM. The synergistic effect between NM and Ag@AgCl optimized the photogenerated carrier separation path. This work provided a new vision for the practical application of efficient photocatalytic N2 reduction.

1D/2D Bi2O3/Ov-Bi2MoO6 p-n junction for efficient photocatalytic N2 fixation

Defected-mediated photocatalytic systems show great potential in photocatalytic N2 reduction for ammonia synthesis. In this work, 1D/2D Bi2O3/oxygen vacancies mediated Bi2MoO6 p-n junctions were constructed by decorating Bi2MoO6 nanosheets onto the surface of Bi2O3 nanorods for ammonia photosynthesis. The crystal structure, morphology, optical properties, and charge transportation behavior were systematically investigated. Taking advantage of the synergistic effect of the existence of oxygen vacancies, enlarged specific surface areas, and improved charge separation, the constructed Bi2O3/Bi2MoO6 p-n junctions exhibited superior photocatalytic N2 reduction performance. The ammonia generation rate of the synthesized BBM3 was found to be significantly higher, with values 4.12 and 2.81 times greater than those observed for pure Bi2O3 and Bi2MoO6. The pathway for the transfer of charges across the p-n junction has been proposed through the analysis of band edge position measurements and in-situ XPS. This work offers novel perspectives on the development of Bi-based photocatalytic systems for ammonia photosynthesis.

Modelling Photocatalytic N2 Reduction to Ammonia: Where We Stand and Where We Are Going.

Artificial ammonia synthesis via the Haber-Bosch process is environmentally problematic due to the high energy consumption and corresponding CO emissions, produced during the reaction and before hand in hydrogen production upon methane steam reforming. Photocatalytic nitrogen fixation as a greener alternative to the conventional Haber-Bosch process enables us to perform nitrogen reduction reaction (NRR) under mild conditions, harnessing light as the energy source. Herein, we systematically review first-principles calculations used to determine the electronic/optical properties of photocatalysts, N2 adsorption and to expound possible NRR mechanisms. The most commonly studied photocatalysts for nitrogen fixation are usually modified with dopants, defects, co-catalysts and Z-scheme heterojunctions to prevent charge carrier recombination, improve charge separation efficiency and adjust a band gap to for utilizing a broader light spectrum. Most studies at the atomistic level of modeling are grounded upon density functional theory (DFT) calculations, wholly foregoing excitation effects paramount in photocatalysis. Hence, there is a dire need to consider methods beyond DFT to study the excited state properties more accurately. Furthermore, a few studies have been examined, which include higher level kinetics and macroscale simulations. Ultimately, we show there is still ample room for improvement with regard to first principles calculations and their integration in multiscale models.

The construction of Cs3MoxSbyBr9/BiVO4 S-scheme heterojunction photocatalyst for efficient photocatalytic N2 fixation

Synergistic nitrogen (N2) reduction with water (H2O) oxidation is meaningful but challenging owing to the inertness of the N2 molecule and the sluggish kinetics of H2O oxidation. Herein, a simutaneous-promotion strategy of redox capacities is presented for constructing a lead-free Cs3Sb2Br9-based S-scheme heterojunction, by decorating Mo-functionalized Cs3Sb2Br9 nanocrystals (Cs3MoxSbyBr9) on BiVO4 nanosheet through an in-situ plane-to-point growth manner. The Mo-functionalization for Cs3Sb2Br9 enables the regulation of the d-band center position, greatly improving surface reaction kinetics for N2 reduction. Furthermore, the construction of the S-scheme heterojunction enhances the driving force for H2O oxidation and spatial charge separation of photocatalysts. As anticipated, the resultant Cs3MoxSbyBr9/BiVO4 exhibits an excellent photocatalytic N2 reduction activity under ambient atmosphere, achieving ammonia (NH3) production at a rate of 300 ± 5 μmol g−1 h−1 under simulated sunlight illumination (100 mW cm−2), which is nearly 20-fold higher than that of pristine Cs3Sb2Br9.

Facile fabrication of carbon supported Bi2O3-BiOCl-Bi heterostructure to boost ammonia under visible light

In this paper, carbon supported Bi2O3-BiOCl-Bi heterostructures were successfully synthesized via a facile and simple hydrothermal method. A series of structure and morphology testing clearly showed that carbon and metallic Bi were deposited on the surface margin of Bi2O3-BiOCl, which benefited the rapid transfer of internal photogenerated electrons. Photophysical experiments including electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS) indicated that the amount of surface oxygen vacancies (OVs) was significantly increased, which act as reactive active sites and therefore effectively enhance the photocatalytic performance. The photocatalytic N2 reduction yield of C@Bi2O3-BiOCl-Bi was remarkably improved to 400 μg·L−1, which was 3.63 times higher than that of BiOCl. This research demonstrated a feasible strategy to construct advanced photocatalyst by incorporating defect-rich structures and surface engineering.

Bimetallic NH2-MIL-101(Fe, Co) as highly efficient photocatalyst for nitrogen fixation

Developing effective catalysts for N2 photofixation at ambient conditions is highly desirable but still challenging. Herein, we reported a novel Co-doped NH2-MIL-101(Fe) (NM-Fe) bimetallic organic framework (BMOF) for visible-light-driven catalytic N2 fixation. It was found that the doping of Co ions could effectively enhance light-harvesting, reduce the conduction band potential, suppress the recombination of photogenerated carriers, and promote the activation of N2. Consequently, the photocatalytic N2 reduction efficiency of bimetallic NH2-MIL-101(Fe, Co) (NM-Fe-Co) was obviously boosted. The sample with the optical Co/Fe molar ratio of 0.15, namely NM-Fe-0.15Co, enabled an ammonia evolution rate up to 335.7 µmol g−1 h−1 without the aid of any sacrificial agents, a 4.4-fold increase over the monometallic NM-Fe baseline. Additionally, the bimetallic NM-Fe-Co displayed excellent stability. The possible reaction mechanism of nitrogen fixation over NM-Fe-Co was proposed based on in-situ infrared analysis. Our study demonstrates a promising strategy for designing potent MOF-based catalysts for N2 photofixation.

Engineering of local electron properties optimization in single-atom catalysts enabling sustainable photocatalytic conversion of N2 into NH3

Photocatalytic synthesis of ammonia (NH3) from nitrogen (N2) offers a promising strategy for carbon neutrality, as it avoids the energy-intensive and carbon-emitting industrial processes. The exploration of high-efficiency N2 photofixation systems for photocatalytic N2 reduction reaction (pNRR) is critical but it remains a challenge since the lack of rational structural design and atomic-level insights into molecular N2 activation mechanism. Herein, an atomically dispersed single-atom palladium (Pd) active sites decorated oxygen-deficient molybdenum oxide (Pd/MoO3-x) was creatively designed for assessing pNRR performance. Interestingly, the integration of single-atom Pd active sites in MoO3-x can significantly weaken the N≡N bond of adsorbed N2 and effectively lower the activation energy barrier during the pNRR process. This is attributed to the fact that the modified Pd single-atom sites of Pd/MoO3-x play a dominant role in the N2 spontaneous adsorption process as well as possess a remarkable photogenerated electron trapping ability, which could be assisted to inject electrons into N2 antibonding orbital, thus significantly accelerates the reaction kinetics. Consequently, the Pd/MoO3-x photocatalyst reaches an impressive NH3 yield rate of 103.2 μggcat.−1h−1, which is superior to that of pristine MoO3-x (21.2 μggcat.−1h−1) and commercial MoO3 (6.5 μggcat.−1h−1), respectively. The present study not only creates a reliable approach to expand efficient N2 photofixation system under mild conditions through the fabrication of atomically dispersed monometallic active sites, but also offers atomic-level insights into the underlying mechanism of pNRR catalytic process.

Fast Joule heating for transformation of Fe-MIL-125(Ti) to Fe/TiO2 with enhanced photocatalytic activity in N2 fixation

It is critical to develop a highly efficient catalyst for the photocatalytic fixation of nitrogen to produce ammonia under ambient conditions. Herein, we reported on a fast Joule heating (FJH) method to synthesize 1.0 wt% Fe-doped TiO2 (JH Fe/TiO2) derived from MIL-125(Ti). For comparison, Fe/TiO2 calcined in a tube furnace was also prepared (TF Fe/TiO2). The photocatalytic production rate of ammonia on JH Fe/TiO2 was increased to 56.87 μmol g−1 h−1, which was 1.5 times higher than that of TF Fe/TiO2. As detected, FJH might lead to the formation of lattice defects with oxygen vacancies (OVs) formation. These OVs and defects had the potential to act as adsorption and reactive sites for N2. Furthermore, in-situ infrared (FT-IR) along with Density Functional Theory (DFT) simulation were applied to study the possible reaction pathways of photocatalytic reduction of N2. As calculated, the substitution of Feδ+ for Ti4+ with the formation of Fe-Ti dual active sites synergistically interacted with the OVs to facilitate the photocatalytic reduction process. Moreover, an alternative pathway was more favorable for the production of NH3. The reasonable design of Fe-doped transition metal oxides and the proposed Fe-Ti dual active sites opened a new approach for highly efficient photocatalytic N2 fixation.

Bi2WO6 Incorporation of g‐C3N4 to Enhance the Photocatalytic N2 Reduction Reaction and Antibiotic Pollutants Removal

Synthesis of ammonia from photocatalytic N2 reduction is challenging due to the fast recombination of electron–hole pairs and the low selectivity of N2 on catalysts. This can be addressed by creating heterojunctions to separate the photogenerated carriers adequately. In this regard, BW/g‐C3N4 is synthesized and the weight percentage of g‐C3N4 is varied. The best photocatalytic activity for N2 reduction reaction (N2RR) is achieved with a ratio of BW/gC3N4 in 3.5:2 ratio, deemed to be the optimized heterojunction. N2‐temperature programmed desorption analysis shows outstanding chemisorption of N2 adsorbed on the BW/g‐C3N4 surface compared to pristine g‐C3N4 and BW. Additionally, forming a heterojunction enhances the charge transfer process and well‐separated electron–hole pairs, significantly boosting the water oxidation process on the catalytic surface. Photoelectrochemical analysis reveals that BW/g‐C3N4 exhibits the shortest hole relaxation lifetime and higher current density than its pristine counterparts. The robust contact between g‐C3N4 and BW reduces the work function of BW/g‐C3N4 based on ultraviolet photoelectron spectroscopy data. Ammonia production with the optimized BW/gC3N4‐3.5:2 is 5.3 and 2.1 times higher than pure g‐C3N4 and Bi2WO6, respectively. Meanwhile, BW/g‐C3N4 demonstrates excellent photocatalytic activity toward antibiotic pollutant degradation as well. After 150 min of visible light irradiation, the removal of 94% ciprofloxacin (CIP) is observed. Finally, a possible mechanism is proposed for photocatalytic N2RR and CIP degradation.

Fluorinated phosphonium ionic liquid boosts the N2-adsorbing ability of TiO2 for efficient photocatalytic NH3 synthesis

A novel ionic liquid ([P4,4,4,4][PF6])–water reaction solution system was constructed, transforming the TiO2−x surface to aerophilic. N2 dissolution and adsorption were promoted, greatly improving N2 fixation performance.

Construction of a BiVO4/VS-MoS2 S-scheme heterojunction for efficient photocatalytic nitrogen fixation.

Photocatalytic nitrogen (N2) reduction to ammonia (NH3), adopting H2O as the electron source, suffers from low efficiency owing to the sluggish kinetics of N2 reduction and the requirement of a substantial thermodynamic driving force. Herein, we present a straightforward approach for the construction of an S-scheme heterojunction of BiVO4/VS-MoS2 to successfully achieve photocatalytic N2 fixation, which is manufactured by coupling an N2-activation component (VS-MoS2 nanosheet) and water-oxidation module (BiVO4 nanocrystal) through electrostatic self-assembly. The VS-MoS2 nanosheet, enriched with sulfur vacancies, plays a pivotal role in facilitating N2 adsorption and activation. Additionally, the construction of the S-scheme heterojunction enhances the driving force for water oxidation and improves charge separation. Under simulated sunlight irradiation (100 mW cm-2), BiVO4/VS-MoS2 exhibits efficient photocatalytic N2 reduction activity with H2O as the proton source, yielding NH3 at a rate of 132.8 μmol g-1 h-1, nearly 7 times higher than that of pure VS-MoS2. This study serves as a noteworthy example of efficient N2 reduction to NH3 under mild conditions.

Au Nanoparticle-Loaded UiO-66 Metal–Organic Framework for Efficient Photocatalytic N2 Fixation

In order to achieve efficient photocatalytic N2 reduction activity for ammonia synthesis, a photochemical strategy was used in this work. UiO-66 was prepared through the solvothermal method and further loaded with Au nanoparticles (Au NPs) onto the UiO-66 (Zr) framework. The experimental results verified that there were metal–support interactions between Au NPs and UiO-66; this could facilitate charge transfer among Au NPs and UiO-66, which was beneficial to enhance the photocatalytic activity. The best N2 fixation effect of Au/UiO-66 with a loading of 1.5 wt% was tested, with a photocatalytic yield of ammonia of 66.28 μmol g−1 h−1 while maintaining good stability. The present work provides a novel approach to enhancing photocatalytic N2 fixation activity by loading NPs onto UiO-66.

Defects-Induced Single-Atom Anchoring on Metal-Organic Frameworks for High-Efficiency Photocatalytic Nitrogen Reduction.

Aiming to improve the photocatalytic activity in N2 fixation to produce ammonia, herein, we proposed a photochemical strategy to fabricate defects, and further deposition of Ru single atoms onto UiO-66 (Zr) framework. Electron-metal-support interactions (EMSI) were built between Ru single atoms and the support via a covalently bonding. EMSI were capable of accelerating charge transfer between Ru SAs and UiO-66, which was favorable for highly-efficiently photocatalytic activity. The photocatalytic production rate of ammonia improved from 4.57 μmol g-1 h-1 to 16.28 μmol g-1 h-1 with the fabrication of defects onto UiO-66, and further to 53.28 μmol g-1 h-1 with Ru-single atoms loading. From the DFT results, it was found that d-orbital electrons of Ru were donated to N2 π✶-antibonding orbital, facilitating the activation of the N≡N triple bond. A distal reaction pathway was probably occurred for the photocatalytic N2 reduction to ammonia on Ru1 /d-UiO-66 (single Ru sites decorated onto the nodes of defective UiO-66), and the first step of hydrogenation of N2 was the reaction determination step. This work shed a light on improving the photocatalytic activity via feasibly anchoring single atoms on MOF, and provided more evidences to understand the reaction mechanism in photocatalytic reduction of N2 .

Defects‐Induced Single‐Atom Anchoring on Metal–Organic Frameworks for High‐Efficiency Photocatalytic Nitrogen Reduction

AbstractAiming to improve the photocatalytic activity in N2 fixation to produce ammonia, herein, we proposed a photochemical strategy to fabricate defects, and further deposition of Ru single atoms onto UiO‐66 (Zr) framework. Electron‐metal‐support interactions (EMSI) were built between Ru single atoms and the support via a covalently bonding. EMSI were capable of accelerating charge transfer between Ru SAs and UiO‐66, which was favorable for highly‐efficiently photocatalytic activity. The photocatalytic production rate of ammonia improved from 4.57 μmol g−1 h−1 to 16.28 μmol g−1 h−1 with the fabrication of defects onto UiO‐66, and further to 53.28 μmol g−1 h−1 with Ru‐single atoms loading. From the DFT results, it was found that d‐orbital electrons of Ru were donated to N2 π✶‐antibonding orbital, facilitating the activation of the N≡N triple bond. A distal reaction pathway was probably occurred for the photocatalytic N2 reduction to ammonia on Ru1/d‐UiO‐66 (single Ru sites decorated onto the nodes of defective UiO‐66), and the first step of hydrogenation of N2 was the reaction determination step. This work shed a light on improving the photocatalytic activity via feasibly anchoring single atoms on MOF, and provided more evidences to understand the reaction mechanism in photocatalytic reduction of N2.

Multifunctional metal (Ag, Bi)-organic frameworks: a versatile platform for photocatalytic degradation, CO2 and N2 reduction, and enhanced antibacterial applications

The facile synthesis of a bimetallic-organic framework is successfully established to portray an efficient catalyst in photocatalytic degradation and photoreduction of nitrogen (N2) and carbon dioxide (CO2) and with antibacterial properties. In the current study, a novel B-BTC (where B represents Ag and Bi) organic framework was successfully synthesized and opted for advanced characterizations. The high-resolution transmission electron microscopy and X-ray photon spectroscopy illustrate the heterostructure formation, whereas X-ray diffraction spectroscopy, zeta sizer, and zeta potential were used to reveal the crystallinity, polydispersity, and average size of the nanomaterial. The material was characterized for photoluminescence analysis to understand the recombination rate and has been compared with the Bi-organic framework. B-BTC was further opted to determine the photocatalytic efficacy, through photocatalytic degradation of amoxicillin (AMX), photocatalytic reduction of N2 to ammonia (NH3), photoreduction of CO2, and antibacterial disinfection. The catalyst showcased ∼90% degradation of AMX under light-emitting diode light irradiation for 60 min. Successful photoreduction of N2 and CO2 showcases a fair generation of NH3 and value-added hydrocarbons, respectively. For each photocatalytic application, a mechanism has been knitted for understanding the overall reactions concerning the proposed reactions. Interestingly, the catalyst also showcased excellent antibacterial activity toward Escherichia coli and Staphylococcus aureus, with a proposed mechanism.

Efficient photocatalytic nitrogen fixation over novel 2D/2D Bi12O17Br2/ZnCr layered double hydroxide heterojunction

Herein, a novel ultrathin 2D/2D heterostructure, Bi12O17Br2 with oxygen vacancies/ZnCr layered double hydroxides (Vo-Bi12O17Br2/ZnCr-LDHs, Vo-BZ) is prepared by solvothermal and coprecipitation methods for photocatalytic reduction of N2 to NH3. The optimal 2D/2D Vo-BZ heterostructure photocatalyst shows production rate of ammonia production of 286.0 μmol·g−1·h−1. It is 12.5 and 3.6 times higher than that of pure ZnCr-LDHs and Vo-Bi12O17Br2. The improved photocatalytic nitrogen reduction performance is attributed to the intimate contact interface, matching bandgap structure, the shortened migration distance, and thus significantly improved separation and transfer efficiency of hole-electron pairs and light adsorption ability. The large number of oxygen vacancies and high specific surface promote the absorption, activation and deionization of N2 molecules. The theoretical simulation calculation indicates that the free energy of nitrogen molecules on the surface of Vo-BZ is favorable for the absorption and activation of N2 molecules. The existence of oxygen vacancies and formation of heterojunctions can dramatically reduce energy barrier of nitrogen molecule hydrogenation process to boost photocatalytic N2 reduction. This study provides a new idea for the development of efficient photocatalytic nitrogen fixing catalysts.