Nonmetal Atoms Research Articles

MOF-derived nanocarbon materials for electrochemical catalysis and their advanced characterization

Because of the demand for clean and sustainable energy sources, nanocarbons, modified carbons and their composite materials derived from metal-organic frameworks (MOFs) are emerging as distinct catalysts for electrocatalytic energy conversion. These materials not only inherit the advantages of MOFs, like customizable dopants and structural diversity, but also effectively prevent the aggregation of nanoparticles of metals and metal oxides during pyrolysis. Consequently, they increase the electrocatalytic efficiency, improve electrical conductivity, and may play a pivotal role in green energy technologies such as fuel cells and metal-air batteries. This review first explores the carbonization mechanism of the MOF-derived carbon-based materials, and then considers 3 key aspects: intrinsic carbon defects, metal and non-metal atom doping, and the synthesis strategies for these materials. We also provide a comprehensive introduction to advanced characterization techniques to better understand the basic electrochemical catalysis processes, including mapping techniques for detecting localized active sites on electrocatalyst surfaces at the micro- to nano-scale and in-situ spectroscopy. Finally, we offer insights into future research concerning their use as electrocatalysts. Our primary objective is to provide a clearer perspective on the current status of MOF-derived carbon-based electrocatalysts and encourage the development of more efficient materials.

The Guidelines for the Design and Synthesis of Transition Metal Atom Doped Carbon Dots.

Atoms doping is a practical approach to modulate the physicochemical properties of carbon dots (CDs) and thus has garnered increasing attention in recent years. Compared to non-metal atoms, transition metal atoms (TMAs) possess more unoccupied orbitals and larger atomic radii. TMAs doping can significantly alter the electronic structure of CDs and bestow them with new intrinsic characteristics. TMAs-doped CDs have exhibited widespread application potential as a new class of single-atom-based nanomaterials. However, challenges remain for the successful preparation and precise design of TMAs-doped CDs. The key to successfully preparing TMA-doped CDs lies in anchoring TMAs to the carbon precursors before the reaction. Herein, taking the formation mechanism of TMAs-doped CDs as a starting point, we systematically summarized the ligands employed for synthesizing TMAs-doped CDs and proposed the synthetic strategy involving multiple ligands. Additionally, we summarize the functional properties imparted to CDs by different TMA dopants to guide the design of TMA-doped CDs with different functional characteristics. Finally, we describe the bottlenecks TMAs-doped CDs face and provide an outlook on their future development.

Operando formation of highly efficient electrocatalysts induced by heteroatom leaching

Heterogeneous nano-electrocatalysts doped with nonmetal atoms have been studied extensively based on the so-called dopant-based active sites, while little attention has been paid to the stability of these dopants under working conditions. In this work, we reveal significantly, when the redox working potential is too low negatively or too high positively, the active sites based on these dopants actually tend to collapse. It means that some previously observed “remarkable catalytic performance” actually originated from some unknown active sites formed in situ. Take the Bi-F for the CO2RR as an example, results show that the observed remarkable activity and stability were not directly from F-based active sites, but the defective Bi sites formed in situ after the dopant leaching. Such a fact is unveiled from several heteroatom-doped nanocatalysts for four typical reactions (CO2RR, HER, ORR, and OER). This work provides insight into the role of dopants in electrocatalysis.

New-type 2D iodine materials with tunable electronic transport impacted by the doping of nonmetal elements

Special structures and good characteristics make 2D iodine structures more appealing and valuable at high pressures. The electrical transport of such 2D iodine structures is theoretically studied here, taking the doping of nonmetal elements into account. Most doped devices show considerably greater equilibrium conductance than the original device. Devices with the dopants in lower atomic numbers show higher conductance. The transmission spectrum all around EF can be improved by the doping of nonmetal elements. Essentially, DDOS can well explain the variations in electron transmission probability caused by the doping of nonmetal atom for most doped devices, serving as one main inherent factor in electron transport. The influence of nonmetal dopants on transmission eigenstates varies according to the main group, essentially depending on the number of transferring channels and the strength of transmission eigenstates. Influenced by the bias, the conductance of such innovative devices fluctuates but with varied amplitudes. Every doping mode can enhance the conductance by applying the bias and such biases for all doping modes must cover lower biases. Unlike the dopants in larger atomic numbers, the devices with the dopants in smaller atomic numbers show much difference in size between the voltage interval that enhances and the voltage interval that weakens. The current grows linearly with bias. Nonmetal doping enables the current to increase at low voltages and decrease at high voltages, compared with the undoped device. The improved and attenuated effect on the current is good for doped devices with nonmetal elements in smaller atomic numbers, but poor in higher atomic numbers. These discoveries contribute significantly to our understanding of the effects of defects and elemental adsorption on electrical characteristics and give strong evidence for the use of new-type 2D iodine materials in controlled electronics and sensors.

Изменение состава твердых нестехиометрических соединений методом ионного переноса

The paper presents results of measuring electron and ion transfer numbers of titanium hydride, carbide and nitride. It is shown that these compounds had mixed electron-ionic (anionic) conductivity. The dependences of the ion transfer number on the non-metal content in titanium carbide and nitride were obtained, and the change of the non-metal content under the influence of an electric field was studied. The non-metal atoms in non-stoichiometric titanium carbide and nitride were located in the octahedral voids of the titanium cubic lattice, forming a non-metal sublattice. Non-stoichiometric titanium hydride had a fluorite-type cubic crystal lattice, and the hydrogen atoms were located in the tetrahedral voids of the cubic titanium lattice. In titanium boride, ionic conductivity appeared near compounds of stoichiometric composition. It is shown that the formation of interstitial phases corresponded to the Hegg criterion. Due to the existence of vacancies in the non-metal sublattice, ion transfer was possible under the influence of an electric field, resulting in a chemical composition change of non-stoichiometric compounds. Analysis of the physicochemical properties of non-stoichiometric transition metal compounds was carried out as an opportunity to detect the ionic conductivity of carbides, nitrides and oxides.

The rational co-doping strategy of transition metal and non-metal atoms on g-CN for highly efficient hydrogen evolution by DFT and machine learning

As a clean energy source, hydrogen has attracted high interest in developing efficient hydrogen evolution reaction (HER) catalysts due to its sustainable and renewable characteristics. In this work, we have systematically investigated the HER activity of the g-CN two-dimensional materials. The catalytic activity in HER is enhanced by doping non-metallic atoms (C, N, B, Si) and transition metal atoms (Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) in the vacancies of g-CN. Based on the first principle calculation, we screened 40 structures and found that the ΔGH* of Sc@C3–CN, V@C3–CN, Mn@C3–CN, Sc@N3–CN, and Ti@Si3–CN was close to zero. Among them, Ti@Si3–CN has the lowest Gibbs free energy change (−0.01 eV) and has excellent HER performance. In addition, we explored HER activity's origin by using machine learning (ML) algorithms. The results show that the atomic relative distance in the TM@X3-CN structure significantly affects the catalytic activity.

The Current State of Research in the Field of Obtaining Semiconductor Materials and Prospects for Development

Due to the increase in the world's population and production volumes, the demand for energy is also increasing year by year. The use of solar energy is one of the most effective ways to solve the energy problems of the countries of the world, as well as our Republic. Solar energy is one of the cheap and environmentally friendly resources, and it is important to create cheap and promising solar cells based on inorganic and organic semiconductor materials. Research and development work is being carried out around the world aimed at the creation and production of new solar cells based on semiconductor polymers and phthalocyanine-based dyes. In this regard, solar cells obtained from light-sensitive dyes based on semiconductor polymer materials, metal and non-metal atoms, and phthalocyanine dyes are among the solar cells currently available due to their flexibility, simple design, environmental friendliness and economy. Improving the efficiency of composites based on organic semiconductor compounds, determining their physico-chemical and operational properties, identifying semiconductor polymers and phthalocyanine-based dyes that can replace silicon-based solar panels put into production as solar cells a large-scale research and development work is being carried out on the use of solar elements in the extraction of solar cells.

Coordination engineering of single-atom ruthenium in 2D MoS2 for enhanced hydrogen evolution.

This study investigates the enhancement of catalytic activity in single-atom catalysts (SACs) through coordination engineering. By introducing non-metallic atoms (X = N, O, or F) into the basal plane of MoS2 via defect engineering and subsequently anchoring hetero-metallic Ru atoms, we created 10 types of non-metal-coordinated Ru SACs (Ru-X-MoS2). Computations indicate that non-metal atom X significantly modifies the electronic structure of Ru, optimizing the hydrogen evolution reaction (HER). Across acidic, neutral, and alkaline electrolytes, Ru-X-MoS2 catalysts exhibit significantly improved HER performance compared with Ru-MoS2, even surpassing commercial Pt/C catalysts. Among these, the Ru-O-MoS2 catalyst, characterized by its asymmetrically coordinated O2-Ru-S1 active sites, demonstrates the most favorable electrocatalytic behavior and exceptional stability across all pH ranges. Consequently, single-atom coordination engineering presents a powerful strategy for enhancing SAC catalytic performance, with promising applications in various fields.

Single-layer PtSe2 adsorbed with non-metallic atoms: geometrical, mechanical, electronic and optical properties and strain effects.

Recently, single-layer PtSe2, possessing high carrier mobility and optical response, has been successfully fabricated. To further expand its application scope and find new physics, in this work, we functionalized it via the adsorption of non-metallic atoms X (X = H, B, C, N, O, and F) to form hybrid systems X-PtSe2, and their geometrical, mechanical, electronic, and optical properties as well as strain tuning effects were studied deeply. Calculations show that the energy stability of X-PtSe2 systems is significantly enhanced, and they also hold higher thermal and mechanical stability. Particularly, X-PtSe2 systems present excellent in-plane tenacity and out-of plane stiffness against deformations, which make them more applicable for designing nanodevices. Intrinsic PtSe2 is a semiconductor, while the X-PtSe2 system can be a band-gap narrowed semiconductor or metal, thus expanding the application scope for PtSe2, and the odd-even effect of electronic phase variation related to the atomic number is found. Besides, the wavelength range of optical adsorption is increased in X-PtSe2 systems, implying that its optical response region is wide, providing more options for developing optoelectronic devices. Moreover, it is shown that strain can flexibly tune the electronic property of X-PtSe2 systems, especially enhancing the optical absorption ability substantially, beneficial for their applications in solar devices.

Harnessing halogen bond donors for enhanced nitrogen reduction: a case study on metal-free boron nitride single-atom catalysts.

Developing efficient catalysts for ammonia synthesis is increasingly crucial but remains a formidable challenge due to the lack of robust design criteria, particularly in addressing the activity and selectivity issues, especially in electrochemical nitrogen reduction reactions (NRR). In this study, we systematically investigated the catalytic potential of hexagonal boron nitride (BN) embedded with non-metal (C, Si, P and S) atoms as an electrocatalyst for the nitrogen reduction reaction using density functional theory (DFT) computations. The preference for non-metal-doped BN nanomaterials stems from their ability to suppress hydrogen evolution and their environmentally friendly nature, in contrast to transition metals. Among the designed single-atom catalysts (SACs), Si-doped boron nitride (SiBBN) exhibits a favorable inclination toward activating nitrogen, which is determined by the combination of advantageous molecular orbital coupling and formation of a covalent bond with the N2 molecule. Under thermal conditions, the first protonation step emerges as the rate-determining step (22.66 kcal mol-1) for SiBBN. Conversely, under electrochemical conditions, the final elementary step becomes the potential-determining step (PDS) with 2.38 eV. We explored the impact of the exogenous addition of Lewis acids (alkali metal ions, neutral boron Lewis acids, and halogen bond donors) on modulating the electrochemical NRR activity. Our results highlight the pivotal role of halogen bond donors as catalytic promoters in facilitating electron density transfer through activated N2, establishing a push-pull charge transfer mechanism that populates the distal nitrogen more than the proximal nitrogen. This facilitates the potential requirements for the first reduction step. The synergistic effect of both halogen bonding and hydrogen bonding interactions in the final reduction step was proven to be the main determinant for a significant reduction in the PDS from 2.38 to 0.10 V. Notably, this study unveils the pioneering role of halogen bond donors as promoters for NRR, providing valuable insights into the development of robust metal-free catalysts and promoters in experimental research.

Theoretical insights into the effect of surface structure and anion ordering on the properties of SrTaO2N for photocatalytic water splitting

AbstractAs one of the representative perovskite‐type oxynitride photocatalysts, SrTaO2N has the ability to split water in the visible‐light region. It was found that the surface modification and interfacial design of SrTaO2N‐based materials are closely related to the photocatalytic activity, but the microscopic mechanisms of these experimental phenomena are not well understood. In this work, we have utilized density functional theory (DFT) calculations to investigate the effect of anion ordering and exposed terminations on the electronic structures, optical absorption, water adsorption and the mechanisms of water oxidation and reduction reactions of SrTaO2N. Our results indicate that cis configurations are more stable than trans configurations. The anion ordering has an important effect on the band gap and optical absorption coefficient. The terminations with exposed Ta atoms are more stable and have bigger work functions than those with exposed Sr atoms possibly due to the bonding ionicity and surface dipoles. The dissociative adsorption of water is energetically more favorable than the molecular adsorption on most surfaces. The highly active sites of hydrogen evolution reaction (HER) are the exposed nonmetal atoms. Terminations with exposed Sr and N atoms have lower overpotentials (0.70–0.77 V) of oxygen evolution reaction (OER) than others. They are comparable to the calculated results of common photocatalysts, such as Co3O4 and TiO2. This study sheds light on the relationship between the termination structure with different anion orders and the photocatalysis‐related properties of SrTaO2N at a molecular level, which provides guidance for constructing highly active photocatalytic materials.

Insights into the coordination-driven role of boron in Fe-doped carbon nitride composites activation of peracetic acid to remove tetracycline: Function and contribution of boron

The coordination strategy of non-metallic atoms was recognized as a great potential for improving the catalytic performance and stability of metal catalysts, although it remained a daunting task. We described a rational design for the introduction of coordinated Boron (B) atoms in Fe-g-C3N4 herein. The resulting FeB5-g-C3N4/PAA system exhibited glorious catalytic activity, removing 96.5 % of tetracycline (TC) within 60 min, surpassing the performance of the Fe-g-C3N4/PAA system by a factor of 1.36. In addition, the system has good acid resistance (pH=3–9) and interference resistance (HCO3-, HPO42-, Cl- and HA), while reduced toxicity of TC and leaching of ferric ions. Notably, B broke the inert electronic structure of graphitic carbon nitride (g-C3N4) and enhanced the electron transfer potential of FeB5-g-C3N4. The coordinated B atoms also had a profound effect on the Fe sites, which not only increased the Fe(II) content but also strengthened the electron-loss potential and PAA adsorption affinity. It served as a TC adsorption site to enhance the adsorption of TC simultaneously. These contributions not only accelerated the regeneration of the Fe(II)/Fe(III) redox cycle but also led to the conversion of high-valent iron oxide species and R-O· into main active species, which played crucial roles in the removal of TC. In summary, this study offered insight into the role and contribution of B on metal catalysts, and it has showcased the practical potential of the FeB5-g-C3N4/PAA process for wastewater treatment applications.

A computational insight on the aromatic amino acids conjugation with [Cp*Rh(H2O)3]2+ by using the meta-dynamics/FMO3 approach

ContextRh(III) complexes demonstrated to exert promising pharmacological effects with potential applications as anti-cancer, anti-bacterial, and antimicrobial agents. One important Rh(III)-ligand is the pentamethylcyclopentadienyl (Cp*) group forming in water the [Cp*Rh(H2O)3]2+ complex. Among of its attractive chemical properties is the ability to react specifically with Tyr amino acid side chain of G-protein–coupled receptor (GPCR) peptides by means of highly chemoselective bioconjugation reaction, at room temperature and at pH 5–6. In this computational work, in order to deepen the mechanism of this chemoselective conjugation, we study the ligand exchange reaction between [Cp*Rh(H2O)3]2+ and three small molecules, namely p-cresol, 3-methylimidazole, and toluene, selected as mimetic of aromatic side chains of tyrosine (Tyr), tryptophan (Trp) and phenylalanine (Phe), respectively. Our outcomes suggest that the high selectivity for Tyr side chain might be related to OH group able to affect both thermodynamic and kinetic of ligand exchange reaction, due to its ability to act as both H bond acceptor and donor. These mechanistic aspects can be used to design new metal drugs containing the [Cp*Rh]2+ scaffold targeting specifically Tyr residues involved in biological/pathological processes such as phosphorylation by means of Tyr-kinase enzyme and protein–protein interactions.MethodsThe geometry of three encounter complexes and product adducts were optimized at the B3LYP//CPCM/ωB97X-D level of theory, adopting the 6-311+G(d,p) basis set for all non-metal atoms and the LANL2DZ pseudopotential for the Rh atom. Meta-dynamics RMSD (MTD(RMSD)) calculations at GFN2-xTB level of theory were performed in NVT conditions at 298.15 K to investigate the bioconjugation reactions (simulation time: 100 ps; integration step 2.0; implicit solvent model: GBSA). The MTD(RMSD) simulation was performed in two replicates for each encounter complex. Final representative subsets of 100 structures for each run were gained with a sampling rate of 1 ps and analyzed by performing single point calculations using the FMO3 method at RI-MP2/6-311G//PCM[1] level of theory, adopting the MCP-TZP core potential for Rh atom.

Effect of doping and defects on the optoelectronic properties of ZrSe2 based on the first principle.

Based on the first principles under the framework of density functional theory, it calculates the effect of vacancy defects in single Zr and single Se atoms and the replacement of Se atoms in ZrSe2 with O, Se, and Te atoms on the optoelectronic properties of monolayer ZrSe2, including geometry, energy band structure, electronic density of states, and optical properties. The doping of the three non-metallic atoms was n-type doping for the O and S atoms and p-type doping for the Te atom. Defects in the Zr atoms and O-atom doping significantly affect the peak reflectance and absorption coefficient of the ZrSe2 system. All Density Functional Theory calculations were carried out using the CASTEP module in the Materials-Studio (MS) software. The generalized gradient approximation plane-wave pseudopotential method and the Perdew-Burke-Ernzerfhof (PBE) generalized function were used for structural optimization and total energy calculation of the defect and doping systems. After convergence tests, the plane wave truncation energy was set to 500eV, and the Brillouin zone K-point grid was set to 4 × 4 × 1. The atomic energy convergence criterion is 1.0 × 10-6eV/atom, the interatomic interaction force convergence criterion is 0.02eV/Å, the maximum atomic displacement convergence criterion is 0.001Å, and the internal crystal stress convergence criterion is 0.05 GPa. In order to avoid the influence of the interaction forces between the layers, a vacuum layer of 15Å is placed in the Z-axis direction.

Rational design single-atom modified Zr2CO2 MXene as a promising catalyst for nitrogen reduction reaction

Renewable production of ammonia via the electrocatalytic nitrogen reduction reaction (NRR) is highly desirable. However, rational design of electrocatalysts with high promising activity under ambient conditions is a challenging subject. In this work, the stability, NRR activity and selectivity of single transition metal (TM, TM = Ti, V, Fe, Ni, Nb, Mo, Ru, and W), nonmetal B and N, and TM and N3 co-modification Zr2CO2 (named TM/Zr2CO2, B(N)/Zr2CO2, and TMN3/Zr2CO2, respectively) are investigated by density functional theory (DFT) calculations. The results revealed that single atom (both transition metal and nonmetal atoms) modification can greatly enhance the NRR catalytic activity and selectivity of original Zr2CO2, and different nonmetal doping concentration can deliver different NRR activity by adjust the interaction strength between doping atom and Zr atom. Among the studied materials, W/Zr2CO2 possesses the highest NRR performance via the distal pathway with the NRR overpotential (ηNRR) of 0.14 V, B/Zr2CO2 possesses the highest NRR performance (ηNRR = 0.26 V) and selectivity via the enzymatic pathway, and for the co-doped systems, RuN3/Zr2CO2 delivers the highest NRR activity with the corresponding ηNRR of 0.54 V. The crystal orbital Hamilton population (COHP), density of states, charge transfers, and work function (Φ) results indicated that the TM and nonmetal atoms can adjust the electronic properties of the Zr2CO2 surface to break the inertness of N2 and form the key intermediate *NNH or *N-*NH, and therefore enhance their NRR activity. The ab initio molecular dynamics (AIMD) simulation results suggested that the structures of the modified Zr2CO2 are dynamically stable at reaction temperature. These results indicated that the proposed surface modifications by W and nonmetal B are the effective approaches for achieving promising NRR electrocatalysts for N2 fixation.

Zn-decorated S,P,B co-doped C2N nanosheet for ibuprofen adsorption: Experimental and density functional theory calculation

Co-doping and decoration methods were simultaneously employed to enhance the adsorption capability of C2N nanosheet for Ibuprofen (IB) removal, as demonstrated through an experimental study and density functional theory (DFT) calculations. Nonmetal atoms (S, P, and B) were successfully co-doped into the C2N nanosheet. Then, the S,P,B co-doped C2N (SPB@C2N) nanosheet was decorated using a Zn atom to enhance the IB adsorption ability of the SPB@C2N nanosheet. The adsorption capabilities of Zn-decorated SPB@C2N (Zn-SPB@C2N), SPB@C2N, and C2N nanosheets were evaluated to recognize the most effective adsorbent for IB removal. Zn-SPB@C2N had a higher adsorption capacity (257.31 mg/g) than SPB@C2N (114.07 mg/g) and C2N (92.96 mg/g). In contrast to other nanosheets that formed hydrogen bonds with the IB structure, the Zn-SPB@C2N nanosheet strongly interacted with the IB structure by forming a covalent bond. The Zn-SPB@C2N nanosheet revealed a much lower band structure (0.01 eV) compared to the SPB@C2N (0.39 eV) and C2N (1.53 eV) nanosheets. This feature highlights the ability of the Zn-SPB@C2N nanosheet to function as an exceptional adsorbent with excellent chemical reactivity for water treatment.

Hydrogen adsorption on vacancy-bent graphene nanosheets: A DFT study

In this study, we have investigated density functional theory calculations on the hydrogen adsorption capacity of pristine graphene nanosheets (GNs), vacancy-bent graphene nanosheets (VGNs), and non-metal atom (boron, nitrogen) doped in vacancy-bent graphene nanosheets (Xy/VGNs, where X is boron (B) and nitrogen (N) and y = 1,2,3 i.e., number of dopant atom). According to previous studies, the presence of vacancy improves the reactivity in the graphene monolayer towards adsorbents. Engineering the vacancy-bent graphene nanostructure with an increased concentration of dopants (B/N) is found to enhance the adsorption capacity of hydrogen linearly. For B3/VGNs, N1-N3/VGNs configurations, the binding energy of hydrogen molecules lies in the useful range of −0.206 eV to −0.286 eV. Electronic property investigation reveals an indirect bandgap in VGNs and B2/VGNs, with other Xv/ VGNs retaining metallic character. The PDOS of N3/VGNs shows higher C(p)-N(p) interaction (graphene-nitrogen) at the vicinity of the Fermi level, favouring increased hydrogen adsorption. Furthermore, molecular dynamics (MD) simulation studies confirm stable adsorption of H2 with low potential energy at a higher temperature of 450 K for N3/VGNs system. This theoretical modelling suggests N3/VGNs to be the most efficient configuration with higher affinity and stability towards hydrogen molecule interaction.

Investigation on the spintronic for armchair-shaped δ-graphyne induced by multiple doping with a transverse electric field

Graphyne holds a potential spintronic application for its unusual elastic and rich electrical properties. We investigate the electronic band structure of armchair-shaped δ-graphyne nanoribbon (AδGYNR) with an applied electric field. Based on the computational data, the results of AδGYNRs with nonmetallic and metallic doping and the intrinsic mechanism of electrical properties have been analyzed. It is discovered that the nonmetallic (B, P) and metallic (Co, Ni, Cu) atoms doping of AδGYNRs can reduce the band gap of system to almost zero, resulting in an obvious spin-splitting behavior. Besides, the electric conductivity of the AδGYNRs with atomic doping at the sp-site is better than the one at the sp2-site. Above all, after applying a transverse electric field to doped AδGYNR, our results reveal that the width of band gap may vary linearly with the intensity of the electric field, in which case the Ni1-doped AδGYNR transforms into semiconductor with a narrow band and the band gap decreases from 0.55 to 0.17 eV, thus our research could beconduciveto effectively modulating the width of band gap of AδGYNRs. Our findings will help to the future development of micro- andnano-electronicdevices based on AδGYNR.

Metal to non-metal sites of metallic sulfides switching products from CO to CH4 for photocatalytic CO2 reduction

The active center for the adsorption and activation of carbon dioxide plays a vital role in the conversion and product selectivity of photocatalytic CO2 reduction. Here, we find multiple metal sulfides CuInSnS4 octahedral nanocrystal with exposed (1 1 1) plane for the selectively photocatalytic CO2 reduction to methane. Still, the product is switched to carbon monoxide on the corresponding individual metal sulfides In2S3, SnS2, and Cu2S. Unlike the common metal or defects as active sites, the non-metal sulfur atom in CuInSnS4 is revealed to be the adsorption center for responding to the selectivity of CH4 products. The carbon atom of CO2 adsorbed on the electron-poor sulfur atom of CuInSnS4 is favorable for stabilizing the intermediates and thus promotes the conversion of CO2 to CH4. Both the activity and selectivity of CH4 products over the pristine CuInSnS4 nanocrystal can be further improved by the modification of with various co-catalysts to enhance the separation of the photogenerated charge carrier. This work provides a non-metal active site to determine the conversion and selectivity of photocatalytic CO2 reduction.

First principles insight on enhanced photocatalytic performance of sulfur-doped bismuth oxide iodate

Bismuth oxide iodate photocatalyst is mostly limited in photocatalytic applications due to its large band gap. Doping by metal and nonmetal ions is one of the simplest and most effective ways to solve the problem. The effect mechanism of nonmetallic sulfur atoms doping on the BiOIO3 semiconductor was studied via the first principles of density functional theory (DFT). A series of doping sites were determined, and the differences in energy band structure, density of states, and light absorption spectra of BiOIO3crystals after sulfur doping were carefully investigated. The doping of any oxygen site may cause the crystal conduction band position to move down, reduce the energy band gap, and the energy required for electron transition is easier to meet, which enhances the photocatalytic activity of the semiconductor. Iodine site doping gives a more reasonable crystal formation energy than substituting oxygen site doping. Moreover, the crystal with iodine doping will introduce obvious impurity states around the Fermi level, and the impurity level can act as a bridge for the electron transition. This work is also helpful in understanding the improvement of photocatalytic performance through crystal doping modification.