Suitable Band Research Articles

Te@Se Core-Shell Heterostructures with Tunable Shell Thickness for Ultra-Stable NO2 Detection.

An effective long-term nitrogen dioxide (NO2) monitoring at trace concentration is critical for protecting the ecological environment and public health. Tellurium (Te), as a recently discovered 2D elemental material, is promising for NO2 detection because of its suitable band structure for gas adsorption and charge mobility. However, the high activity of Te leads to poor stability in ambient and harsh conditions, limiting its application as a gas-sensitive material. Herein, 2D single-elemental Te@Se heterostructures with a core-shell structure are prepared using a solvothermal method. The Te@Se heterostructures demonstrate an extremely high response of 622% to 1 ppm of NO2 at room temperature, with ultrafast response/recovery times of 10 s/30 s. Moreover, the core-shell heterostructures exhibit excellent stability in NO2 sensing performance over a period of 90 days. The success relies on the ultrathin Se shell with a thickness of 4-6 nm on Te, which enables the efficient redistribution and transport of interfacial charges. These findings reveal the potential of single-element core-shell heterojunctions to achieve high-performance gas sensing, paving the way for advancements in NO2 detection materials.

Layered double hydroxide modified bismuth vanadate as an efficient photoanode for enhancing photoelectrochemical water splitting.

Photoelectrochemical (PEC) water splitting has attracted significant interest as a promising approach for producing clean and sustainable hydrogen fuel. An efficient photoanode is critical for enhancing PEC water splitting. Bismuth vanadate (BiVO4) is a widely recognized photoanode for PEC applications due to its visible light absorption, suitable valence band position for water oxidation, and outstanding potential for modifications. Nevertheless, sluggish water oxidation rates, severe charge recombination, limited hole diffusion length, and inadequate electron transport properties restrict the PEC performance of BiVO4. To surmount these constraints, incorporating layered double hydroxides (LDHs) onto BiVO4 photoanodes has emerged as a promising approach for enhancing the performance. Herein, the latest advancements in employing LDHs to decorate BiVO4 photoanodes for enhancing PEC water splitting have been thoroughly studied and outlined. Initially, the fundamental principles of PEC water splitting and the roles of LDHs are summarized. Secondly, it covers the development of different composite structures, including BiVO4 combined with bimetallic and trimetallic LDHs, as well as other BiVO4-based composites such as BiVO4/metal oxide, metal sulfide, and various charge transport layers integrated with LDHs. Additionally, LDH composites incorporating materials like graphene, carbon dots, quantum dots, single-atom catalysts, and techniques for surface engineering and LDH exfoliation with BiVO4 are discussed. The research analyzes the design principles of these composites, with a specific focus on how LDHs enhance the performance of BiVO4 by increasing the efficiency and stability through synergistic effects. Finally, challenges and perspectives in future research toward developing efficient and stable BiVO4/LDHs photoelectrodes for PEC water splitting are described.

In Situ Growth of Metal-Organic Layer on Polyoxometalate-etching Cu2O to Boost CO2 Reduction with High Stability.

Low-cost Cu2O with a suitable band gap holds great potential for solar utilization. However severe photocorrosion and weak CO2 capture capability have significantly hindered their application in artificial photosynthesis. Herein, polyoxometalate (POM)-etching and in situ growth of metal-organic framework (MOF) can simultaneously incorporate electron-sponge and HKUST protective layer into Cu2O. The resulting ternary composites Cu2O@POM@HKUST-n (POM = PMo12O40 and PW12O40) with dual hetero-interfaces can efficiently convert CO2 to HCOOH with 5226 µmol g-1 yield, over 5 and 55 times higher than that of Cu2O (1010 µmol g-1) and Cu2O@HKUST (95.02 µmol g-1). In situ XPS and DFT studies reveal that Cu mainly existed in the form of Cu2O and Cu-MOF, while a unique Cux+ (1< x ≤2) surface layer formed upon the Cu2O matrix surrounding POMs for CO2 absorption and activation. Systematic investigations demonstrate that the electron-sponge can efficiently capture electrons from excited Cu2O to promote the generation of a Cux+ surface layer, while the closely surface-coating metal-organic layer can act as protective layer and CO2 adsorbent. This dual function concurrently contributes to promote photocatalysis and prevent Cu2O degradation. Remarkably, the ternary composites exhibit much enhanced photochemical stability and can be used for over 60 h without noticeable activity loss.

Heterojunctions of ZnS with Zn vacancies and hexagonal CdS pyramids for photocatalytic hydrogen production

Metal sulfides with suitable morphology typically possess efficient solar light utilization and suitable band structures for photocatalytic hydrogen production.

Advances in Artificial Photosynthesis: The Role of Chalcogenides and Chalcogenide‐Based Heterostructures

AbstractArtificial photosynthesis, encompassing the photocatalytic generation of H2 and CO2 reduction innovations, seems to be a highly promising approach. This is due to its ability to efficiently transform CO2 into hydrocarbon fuel and valuable chemical products using solar energy as a direct energy source. This will simultaneously help to mitigate global warming and energy shortage issues. Chalcogenide‐based semiconductors have recently gotten a lot of attention as an important area of research for photocatalytic H2 production and CO2 conversion, owing to their low band gap energy, suitable band structures, and a great photoresponsivity spectrum. Modifying chalcogenides into their heterostructures could be a great way to solve problems like photo corrosion and carrier recombination. Therefore, this review summarized a series of different modifications of chalcogenides and recent developments in their photocatalytic and photo electrocatalytic performance, particularly in H2 production and CO2 conversion. Lastly, we discussed the challenges, limitations, areas for development, and future prospects of chalcogenides and their heterostructures capable of utilizing visible light to produce H2 gas and reduce CO2.

Comparative photocatalytic performance of iron nanoparticles biosynthesized from aqueous extracts of potato, potato peels, and leaves.

This study presents an eco-friendly, cost-effective approach for synthesizing highly efficient nanocatalysts with the help of organic waste. Iron nanoparticles (INPs) were synthesized from aqueous extracts of potato, potato peel, and potato leaf and were evaluated for their photocatalytic efficiency for the degradation of methylene blue dye. X-ray Diffraction (XRD) confirmed Fe3O4 nanoparticles cubic crystal structure with the smallest crystallite size (9.52 nm) with potato peel, and Brunauer-Emmett-Teller (BET) analysis also showed the highest surface area (61.2 m2/g) for the same material. At the same time, other characterizations such as Fourier-Transform Infrared Spectroscopy (FTIR), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), and Ultraviolet-Visible Spectroscopy (UV-Vis) for these nanoparticles were also performed, which provided insights into the chemical and physical composition and photoactivity. Photocatalytic tests demonstrated efficient methylene blue (MB) degradation under sunlight for all iron nanoparticles. The iron nanoparticle prepared using potato peel extracts achieved the highest degradation efficiency of 99 % in 120 min, with the highest first-order kinetics K = 0.0426 min-1, attributed to its smallest crystallite size, highest surface area, and suitable band gap.

Optimization of CZTSe Thin Films Using Sequential Annealing in Selenium and Tin-Selenium Environments.

Cu2ZnSnSe4 (CZTSe) is a promising material for thin-film solar cells due to its suitable band gap, high absorption coefficient, and composition of earth-abundant and nontoxic elements. In this study, we prepared CZTSe thin films from Cu/SnSe2 and ZnSe stacks using a two-step annealing process. Initially, Cu-Sn-Se (CTSe) films were synthesized by sequential deposition and annealing of Cu and SnSe2 precursors in either a selenium (Se) or tin-selenium (Sn+Se) atmosphere. After the deposition of a ZnSe layer on top of CTSe films, the stack underwent a second annealing process, again in either a Se or Sn+Se atmosphere, resulting in four distinct annealing combinations: Se→Se, Sn+Se→Se, Se→Sn+Se, and Sn+Se→Sn+Se. The first annealing step enabled the formation of CTSe, while the second annealing step, performed after ZnSe deposition, led to the formation of the CZTSe phase. Comprehensive characterization including grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrical measurements was conducted. GIXRD and Raman analysis revealed kesterite CZTSe phase peaks, with some samples showing a split in the main peak at ∼27° (2θ), indicating the presence of CuxSe and ZnSe secondary phases. SEM analysis showed the impact of Sn and Se annealing on grain size, with larger grains observed in films annealed in Sn+Se atmospheres, particularly in the second heat treatment process. EDS results displayed consistent elemental composition across samples, with varying Cu/(Zn+Sn), Zn/Sn and Se/metal ratios influencing the band gap values from 1.09 to 1.63 eV. Hall measurements indicated p-type conductivity with carrier concentrations between 1016 and 1023 cm-3. These results highlight the effectiveness of our two-step annealing process, particularly the Sn+Se atmosphere, in optimizing CZTSe thin films for potential use in high-efficiency thin-film solar cells.

Perovskite CsCuClxBr3- x Microcrystals: Band Structure, Photochemical Stability, and Photocatalytic Properties.

Although Pb-based metal halide perovskites (MHPs) have excellent photoelectric characteristics, their toxicity remains a limiting factor for their widespread application. In the paper, a series of CsCuClxBr3-x (x = 1, 2, 3) MHP microcrystals were developed and their hydrogen evolution performance in ethanol and HX (X = Cl, Br) was also studied. Among them, CsCuCl3 microcrystals exhibit high hydrogen evolution performance in both HX and ethanol, attributed to their longest average lifetime and suitable band structure. Additionally, the effect of different sacrificial agents on photocatalytic hydrogen production indicates that the photogenerated hole (h+) plays a critical role. MHPs can maintain a dynamic equilibrium of dissolution and precipitation in HX-saturated aqueous solutions, thereby overcoming the stability issues associated with perovskite. The phase transition of CsCuClxBr3-x during photocatalysis is monitored by the XRD technique. CsCuCl3 shows high stability in saturated HCl aqueous solution, and excellent photocatalytic performance with a hydrogen production rate of CsCuCl3 microcrystals reached 103.98 μmol g-1 at 210 min. Our study expands the development prospects of CsCuCl3 in the field of photocatalytic solar fuel generation.

Ultra-high carrier mobility and ultra-low lattice thermal conductivity in PdSSe monolayers with fully Stone–Wales defects

The Stone–Wales (SW) defects have a critical impact on the physical properties of the carbon-based materials with pentagonal and hexagonal rings, which also emerge in other pentagon-based materials with the Cairo tessellation. However, scarce attention has been paid to SW defect engineering in two-dimensional (2D) pentagonal materials. In the present letter, we propose four unreported 2D PdSSe monolayers (designated as SW1–SW4) by introducing SW defects into the penta-PdSSe monolayer. The electronic structure, optical, electrical transport, and thermal transport properties of these SW defect structures have been systematically investigated based on first-principles calculations. SW1–SW4 retain the square-planar coordination as presented in the pristine penta-PdSSe, exhibiting excellent dynamical, thermal, and mechanical stability. Particularly, SW1 and SW2 exhibit direct bandgaps, which are more favorable for electronic transitions. The suitable band alignments meet the requirement of photocatalytic water splitting. Furthermore, the defect structures show high visible-light absorption coefficients (∼105 cm−1) and ultra-high carrier mobility (∼103 cm2V−1s−1). More excitingly, these defect structures display ultra-low anisotropic lattice thermal conductivities (lower than 2 Wm−1K−1 at room temperature). The suitable bandgap values, appropriate band edge positions, good optical absorption performances, and ultra-high carrier mobility concomitant with ultra-low lattice thermal conductivity render these PdSSe monolayers with SW defect structures as promising semiconductor materials for potential applications in nanoelectronics, optoelectronics, solar cell, photocatalyst, and thermoelectric energy conversions.

Determining the hydrogen production potential of ConMo6Se8 chevrel phases

Abstract In this study, the Co n Mo 6 Se 8 (n = 1, 2, 3, and 4) Chevrel phases are investigated by using Density Functional Theory (DFT) to reveal their potential for photocatalytic hydrogen production. The stability conditions of these phases reveal that CoMo 6 Se 8, Co 2 Mo 6 Se 8, and Co 3 Mo 6 Se 8 satisfy the thermodynamic and mechanic stability properties, while Co 4 Mo 6 Se 8 does not satisfy any of these properties. Furthermore, the formation enthalpy of these phases shows that CoMo 6 Se 8, Co 2 Mo 6 Se 8, and Co 3 Mo 6 Se 8 can be synthesized experimentally due to having negative formation enthalpy values. Furthermore, the thermal stabilities of the machine-learning (ML) force fields are investigated by ab-initio molecular dynamics (AIMD) calculations. The electronic properties of these phases are also investigated in detail, and it is found that Co 3 Mo 6 Se 8 has a suitable band gap for photocatalytic water splitting. Concerning the investigation of the valence band and conduction band levels, it is shown that Co 3 Mo 6 Se 8 has a conduction band minimum level suitable for producing hydrogen. This study is the first attempt to reveal the hydrogen production performance of the Co n Mo 6 Se 8 (n = 1, 2, 3, and 4) Chevrel phases as far as the literature is concerned, paving the ground for future investigations in this field.

Preparation and investigation of 2D/2D black phosphorene/ZnIn2S4 Z‐scheme photocatalysts for enhanced hydrogen evolution

AbstractHeterojunction photocatalytic materials show great promise in hydrogen production from water decomposition under visible light. The selection of components in the heterojunction and the type of heterojunction constructed directly determine the hydrogen production efficiency. In this study, black phosphorene (BP), which has a broad visible light absorption range, and ZnIn2S4 (ZIS), with a suitable band structure, are chosen to design new heterojunction photocatalysts. Through an ultrasound‐assisted solvothermal method, a BP/ZIS heterojunction with a unique layered 2D/2D structure is successfully synthesized. Comprehensive characterization and calculation have elucidated the microstructure and band structure of BP and ZIS, further confirming the formation of a Z‐scheme heterojunction. Such a novel BP/ZIS heterojunction exhibits a remarkable photocatalytic hydrogen evolution rate of 1317 µmol·h−1·g−1, making a 3.35‐fold increase compared to ZIS and superior performance over BP. This enhancement in photocatalytic activity of BP/ZIS heterojunction can be primarily attributed to the enhanced light harvesting and carrier utilization resulting from the formation of the Z‐scheme heterojunction. This work provides new insights for the development of efficient photocatalysts for hydrogen production.

High-Throughput Computing of Janus Chalcogenides as Photocatalysts and Piezoelectric Materials for Overall Water Splitting.

The presence of the intrinsic fields in two-dimensional (2D) materials holds promise for photocatalysts, as it diminishes the band gap requirements of 1.23 eV and accelerates the separation of the photogenerated carriers. Inspired by the extensive application in MA2X4 families, we predict Janus ZMXAY derived from MA2X4 materials to introduce intrinsic fields suitable for photocatalysts from 512 candidates. These monolayers also exhibit high mobilities up to ∼104 cm2V-1s-1 with strong anisotropy, and are accompanied by the inherent piezoelectric properties. Notably, all monolayers, except Janus SMoPGeAs, SeMoPSiAs, and SeMoPGeAs, demonstrate suitable band gaps (0.88-1.43 eV) and appropriate band edge positions without the need for any external potential to drive spontaneous overall water splitting. It also demonstrates visible optical absorption capacity and high solar-to-hydrogen conversion efficiency (16.06-41.08%). Our work identifies ideal candidates for multifunctional devices and provides theoretical guidance for future experimental research and application development.

Mitigating the interface defects influence on SnSe solar cells using optimized electron transport layer

The field of photovoltaics relies heavily on compound semiconductors, particularly those based on selenium. However, challenges in maintaining stoichiometry and the scarcity of elements like Indium and Gallium hinder their widespread adoption. Tin monoselenide (SnSe) emerges as a promising alternative to silicon, thanks to its favorable properties, including a high absorption coefficient, suitable band gap, and excellent chemical stability. Additionally, SnSe exhibits superior thermal stability and can maintain efficiency under a wider range of operating conditions. Its unique crystal structure allows for enhanced charge carrier mobility, facilitating better performance in thin-film applications. These attributes collectively position SnSe as a highly competitive material in the pursuit of efficient and reliable solar energy solutions. Despite its potential, there is a lack of research on low-efficiency solar cells based on SnSe, highlighting the need for further exploration. Our study advocates for a theoretical investigation into the factors affecting SnSe-based solar cell efficiency, focusing on loss mechanisms like bulk and interface recombination. We propose an analytical model that examines various recombination mechanisms and their interactions to enhance efficiency. Experimental results validate our model, revealing the pivotal role of recombination mechanisms at both bulk and interface levels. Besides, the suggested model is used as a fitness function for the Multi Objective Particle Swarm Optimization (MOPSO) technique to identify the optimal combination of design parameters that produced the highest efficiency. The optimized design with In2O3 and MgZnO as Electron transport layer (ETL) materials surpasses current efficiency limitations and explore efficient Cd-free electron transport layer with suitable band alignment. Overall, our strategy by combining analytical model with optimization technique provides insights and solution for enhancing SnSe-based solar cell efficiency, to exceed 13%.

Mixed Metal Oxide Heterojunction for High-Performance Self-Powered Ultraviolet Photodetection.

The field of photoelectrochemical-type (PEC) ultraviolet (UV) photodetectors has witnessed swift progression due to their facile fabrication processes and self-powered function. The realization of high-performance and self-powered PEC UV photodetectors is attractive and challenging. In this study, the application of ZnAl mixed metal oxide (MMO) heterojunctions in self-powered PEC UV photodetectors is introduced for the first time. The MMO heterojunctions are composed of ZnO and ZnAl2O4, which provide a suitable band structure for accelerating the photogenerated carrier separation and transport, boosting UV photodetection. Irradiation of the self-powered MMO PEC UV photodetectors with UV light (365 nm) results in a high responsivity of 46.82 mAW-1 and a fast response time of 18/35 ms. An impressive UV/visible rejection ratio of 1088.8 and excellent multi-cycle stability are demonstrated, exceeding the most recently reported PEC UV photodetectors. Moreover, the MMO PEC UV photodetectors possess underwater optical communication capability, confirming promising potential for underwater optoelectronic devices. This study provides a new perspective on the development of high-performance PEC UV photodetectors.

Construction of MOF@COF Z-scheme heterojunction for efficient photocatalytic degradation of tetracycline in water: synthesis, mechanism, degradation pathway, and DFT calculation

As emerging pollutants, antibiotics in water environment posed a significant threat to human health and ecosystem. A lot of attention has been focused on tetracycline (TC). Photocatalysis, a green and efficient water treatment technology, has shown broad application prospects. Currently, the construction of photocatalytic heterojunctions is often limited to matching suitable energy band structures. However, simple surface doping largely restricted the carriers transport efficiency and stability. In this study, a series of composite photocatalysts (designated as NMSN-x) were prepared by functionalized metal organic framework Ti-MOF and covalent organic framework SNW-1 for TC removal. The schiff-based reaction was employed to achieve covalent linkage between the monomer catalysts, which greatly enhanced the carrier transport efficiency of the composite photocatalysts. Under UV light, the NMSN-1.5 demonstrated impressive removal capability to TC, which removed 93.10 ± 2.86% of TC in 60minutes and achieved 61.37 ± 2.18% under visible light, with up to 76.51 ± 3.37% removal in a natural water background. Carrier separation and transfer was greatly enhanced by the covalent connection between the monomers forming the heterojunction. Combined with density functional theory, the electron transfer mechanism was identified as Z-scheme heterojunction. In addition, the photodegradation intermediates of NMSN-1.5 were assessed to be significantly less environmentally toxic than TC itself. This study introduced a novel strategy for constructing photocatalytic heterojunctions for removal of TC, serving as a valuable reference in the field.Keywords

DFT study of structural, electronic, optical and elastic properties of lead-free Bi based perovskites X2NaBiCl6 (X= K and Rb) with pressure

The pressure dependent structural, electronic, optical and mechanical properties of Bi-based cubic halide double perovskites, X2NaBiCl6 (X = K and Rb) are explored by implementing full-potential linearized augmented plane wave (FP-LAPW) method. At zero pressure, K2NaBiCl6 and Rb2NaBiCl6 posses indirect band gaps of 3.746 and 3.735eV, respectively and the band gaps decrease with increasing pressure for both compounds. The elliptical shape of charge density contours under high pressure ensured a strong covalent bonding between K/Rb and Cl atoms along (110) plane. We explored the essential optical properties for both compounds with different pressures and found a red-shift with increase in pressure. Furthermore, all the values of mechanical parameters, viz. elastic constants and moduli, Vickers hardness, Debye and melting temperatures are enhanced with increasing pressure. Due to suitable band gaps and appropriate mechanical parameters, both perovskites are proved as promising candidates in thermoelectric power generation and high temperature devices.

Cyanobacterial hydrothermal carbonization carbon as photocatalyst for selective aerobic oxidation of cyclohexane

The exploration of catalyst preparation techniques that incorporate environmental-friendly methodologies has consistently been the focus of scientific inquiry within the field of green synthesis of oxygen-containing organic chemicals. Herein, a metal-free hydrothermal carbonation carbon (HTCC) has been prepared utilizing cyanobacterial biomass produced during a water bloom in a freshwater lake. The HTCC produced is capable of performing photocatalytic selective oxidation of cyclohexane to cyclohexanol and cyclohexanone (KA oil) under ambient conditions. The use of cyanobacterial biomass allows for the efficient preparation of HTCC, which exhibits a conversion rate of cyclohexane that is 4.1 times of HTCC prepared with alternative carbon sources (glucose). The selectivity to KA oil over the samples are almost 100%. Characterizations and analysis reveal that cyanobacteria can lead to self-doping of nitrogen and hydrophobicity of the resulting HTCC, while sulfuric acid etching endow it with more photoactive sp2 hybridized structure units that contribute to a higher photogenerated carrier separation efficiency. The suitable band structure enables the cyanobacterial HTCC to produce superoxide radicals to oxidize cyclohexane. These findings are of great significance for the development of eco-friendly photocatalysts and the utilization of biomass resources.

Fabrication of ZnIn2S4/CeO2 S-scheme heterojuntion for the enhanced removal of tetracycline under visible light irradiation

A series of S-scheme ZnIn2S4/x-CeO2 heterojunction were designed and fabricated through in-situ precipitation and hydrothermal method. XRD, SEM, TEM, EDX, XPS, UV-vis DRS and adsorption-photocatalytic techniques were employed to investigate its crystal phase structure, morphology, size, elemental composition, photo-response property and elimination ability for tetracycline. XRD analysis revealed CeO2 and ZnIn2S4 in ZnIn2S4/x-CeO2 sample presented cubic and hexagonal phase structure, respectively. SEM and TEM images indicated that CeO2 particles with irregular-shaped of around 20nm were attached on the smooth surface of ZnIn2S4 microparticles with ca. 4 μm. All the as-synthesized ZnIn2S4/x-CeO2 samples could harvest more visible-light and the absorption edges were red-shifted in comparison with pure CeO2. ZnIn2S4/0.3-CeO2 sample exhibited remarkably enhanced photocatalytic performance and its removal efficiency for tetracycline reached 87.29% within 100min. The detailed experimental and DFT calculation indicated that the enhanced photocatalytic property was mainly ascribed to the synergistic effect of wide light-response range, suitable band position and successful fabrication of S-scheme heterostructure, which was in favor of rapid transfer and available separation of photo-generated e-/h+ pairs. The scavenger experiments and the ESR data revealed that the •O2– and h+ active species played the dominant role in tetracycline removal over ZnIn2S4/0.3-CeO2 system. In addition, the as-synthesized ZnIn2S4/0.3-CeO2 samples had excellent stability and the removal efficiency still reached 70.73% after being repeatedly used for 4 times. Furthermore, the possible enhanced photocatalytic mechanism over ZnIn2S4/x-CeO2 was proposed to get a better understanding of photocatalytic process. This work provided the guidance to fabricate CeO2-based heterojunction with promising prospect for the efficient elimination of antibiotic residues from wastewater.

Built-in electric field microenvironment of nickel cobalt phosphine/carbon nitride heterojunction for the enhanced visible-light-driven photocatalytic CO2 reduction

The greenhouse effect and the shortage of fossil energy are among the major issues that need to be addressed by the international community today. And graphite phase carbon nitride (g-C3N4, CN) is widely applied in catalysis because of its advantages of simple preparation, suitable band structure, high chemical and thermal stability. While some drawbacks limits its widespread application. In this study, different ratios of nickel cobalt phosphine/carbon nitride heterojunction photocatalyst (NiCoP/CN) was prepared by loading different amount NiCoP on the surface of CN using in-situ growth technology. The characterization results of XRD, SEM, TEM and XPS indicated that the synthesized NiCoP/CN heterojunction photocatalyst presented a highly wrinkled structure, which was conducive to the contact between the heterojunction photocatalyst and CO2. The combination of NiCoP with CN generated a unique figure of merit and created a built-in electric field, which facilitates the accumulation of photogenerated electrons in the CN region, thus providing a rich source of reducing electrons for the photocatalytic process. The catalytic reduction activity was assessed by the efficiency of photocatalytic CO2 reduction to simultaneous production of CO and CH4. The results indicated that compared with the original CN, the NiCoP/CN heterojunction photocatalyst exhibited excellent photocatalytic reduction performance of CO2. Among the prepared photocatalysts, the NiCoP-3/CN heterojunction photocatalyst had the best photocatalytic performance with CO and CH4 yields of 874.00 µmol g-1 h-1 and 408.00 µmol g-1 h-1. In addition, NiCoP is a kind of superior electronic conductor, and electrons in CN can effectively move towards NiCoP, which greatly inhibits the photo-induced recombination of charges and improves reduction efficiency.

In situ construction of CuBi-MOF derived heterojunctions with electron-rich effects enhances localized CO2 enrichment integrated with Si photocathodes for CO2 reduction

Photoelectrochemical reduction of CO2 (PEC-CO2RR) to fuels or industrial feedstocks using photocathodes is a promising approach to addressing the climate crisis and energy shortage. The design of photocathode with suitable band structure and robust CO2 capture remains challenging. In this work, a Cu2O@Bi-300 (CuBi-300) catalyst was prepared in situ using Bi-MOF as a template, and a CuBi-300/Si photocathode was constructed. Due to the bridging effect of Cu-O-Bi bonds and the existence of the coordination unsaturated Bi sites, CuBi-300/Si exhibits excellent photoelectrochemical properties and reaction kinetics. The formate yield of CuBi-300/Si (101.1 µmol cm−2 h−1, Faraday efficiency = 95 %) are 10.2 times higher than those of Bi-300/Si at −0.3 V vs RHE, along with excellent stability for 50 hours. In situ FTIR and density functional theory calculations indicate that the Cu2O-induced formation of electron-rich Bi enhances CO2 chemisorption and stabilizes the key intermediate (*COOH). This work presents a novel approach for developing high-performance, low-energy consumption PEC-CO2RR photocathode devices by in situ constructing heterojunctions to simultaneously enhance photovoltaic properties and CO2 adsorption.