Suitable Redox Potential Research Articles

Photocatalytic applications of 2D surface decorated boron phosphides: A density functional theory investigation

Designing high efficiency water splitting photocatalysts remains a great challenge. Base on density functional theory calculations, novel 2D functionalized hexagonal boron phosphides breaking mirror symmetry are demonstrated as free-standing stable nanoflakes. It is systematically demonstrated that bilayer HPBCl and BrPBCl are potential water splitting photocatalysts, due to their moderate band gap, spatial separation of photoexcited carriers, adequate external potential for water redox reactions, and strong visible light absorption. For traditional photocatalysts, the water splitting redox potential demands a band gap limit of EG > 1.23 eV, causing a great waste of infrared light accounting for nearly fifty percentage of the solar energy. Interestingly, bilayer HPBBr, with a small band gap of 0.43 eV, can not only show excellent energy harvest on infrared light as well as on visible light, but also simultaneously provide suitable redox potentials by adjusting pH value.

Single-step synthesis of novel Bi2Fe4O9 nanosheets for high-efficient photocatalytic CO2 reduction to CO

It is rather essential to design efficient semiconductor photocatalytic materials to achieve CO2 green conversion to solar fuels. In this work, novel Bi2Fe4O9 nanosheets are successfully synthesized by a facile hydrothermal method, and applied to the photocatalytic CO2 reduction to CO for the first time. The good nanosheet structure and suitable redox potential of Bi2Fe4O9 bring out not only good photo-effect capability but also effective photo-generated carriers, leading to excellent CO2 photo-reduction activity with CO generation rate of 17.66 μmol·g−1·h−1 (10 h), more than ultramodern reported 13.1 μmol·g−1·h−1 (8 h) of Bi4Ti3O12 hollow-spheres and 3.975 μmol·g−1·h−1 (8 h) of (BiO)2CO3 under simulated sunlight irradiation. More importantly, its performance remains at about 98% after ten consecutive cycle tests, indicating the excellent active stability of Bi2Fe4O9. This work provides new insights into designing and preparation of Bi2Fe4O9-based semiconductor photocatalysts for high-efficient photocatalytic CO2 reduction to CO in the future.

Accurate redox potentials for solvents in Li‐metal batteries and assessment of density functionals

AbstractThe practical applications of Li metal batteries (LMBs) have been limited by the anodic instability which causes fatal problems including low Coulombic efficiency and short cycling lifespan. One way of addressing this issue is to develop new solvents with suitable redox potentials for electrolytes of LMBs. By using the recently developed Wuhan–Minnesota‐scaling method, the work has developed the Redox20 benchmark database consisting of the Ox10 subset of 10 oxidation potentials and the Red10 subset of 10 reduction potentials for four conventional and six fluorinated solvents in LMBs. The performances of 35 DFT methods have been assessed against Redox20. Based on the assessments, M05‐2X, M08‐HX, M08‐SO, M06‐2X, and revM06 functionals are the most accurate for the predictions of oxidation potentials, and the N12, M06‐HF, M08‐HX, HSE06, and PW6B95‐D3 functionals are best performers for calculating reduction potentials. M08‐HX gives the lowest average mean unsigned error, and it is recommended for the calculation of redox potentials. M08‐HX has been employed to calculate the redox potentials and highest occupied molecular orbital/lowest unoccupied molecular orbital structures of 48 solvents for LMBs, which is beneficial to the selection of optimal LMBs electrolyte solvents.

Recent Advances in 2D Heterostructures as Advanced Electrode Materials for Potassium‐Ion Batteries

Owing to the cost‐effectiveness, Earth abundance, and suitable redox potential, potassium‐ion batteries (PIBs) stand out as one of the best candidates for large‐scale energy storage systems. However, the large radius of K+ and the unsatisfied specific capacity are the main challenges for their commercial applications. To address these challenges, constructing heterostructures by selecting and integrating 2D materials as host and other materials as guest are proposed as an emerging strategy to obtain electrode materials with high capacity and long lifespan, thus improving the energy storage capability of PIBs. Recently, numerous studies are devoted to developing 2D‐based heterostructures as electrode materials for PIBs, and significant progress is achieved. However, there is a lack of a review article for systematically summarizing the recent advances and profoundly understanding the relationship between heterostructure electrodes and their performance. In this sense, it is essential to outline the promising advanced features, to summarize the electrochemical properties and performances, and to discuss future research focuses about 2D‐based heterostructures in PIBs.

Upconversion nanoparticles coupled with hierarchical ZnIn2S4 nanorods as a near-infrared responsive photocatalyst for photocatalytic CO2 reduction

Developing near-infrared responsive (NIR) photocatalysts is very important for the development of solar-driven photocatalytic systems. Metal sulfide semiconductors have been extensively used as visible-light responsive photocatalysts for photocatalytic applications owing to their high chemical variety, narrow bandgap and suitable redox potentials, particularly the benchmark ZnIn2S4. However, their potential as NIR-responsive photocatalysts is yet to be reported. Herein, for the first time demonstrated that upconversion nanoparticles can be delicately coupled with hierarchical ZnIn2S4 nanorods (UCNPs/ZIS) to assemble a NIR-responsive composite photocatalyst, and as such composite is verified by ultraviolet–visible diffuse reflectance spectra and upconversion luminescence spectra. As a result, remarkable photocatalytic CO and CH4 production rates of 1500 and 220 nmol g−1h−1, respectively, were detected for the UCNPs/ZIS composite under NIR-light irradiation (λ ≥ 800 nm), which is rarely reported in the literature. The remarkable photocatalytic activity of the UCNPs/ZIS composite can be understood not only because the heterojunction between UCNPs and ZIS can promote the charge separation efficiency, but also the intimate interaction of UCNPs with hierarchical ZIS nanorods can enhance the energy transfer. This finding may open a new avenue to develop more NIR-responsive photocatalysts for various solar energy conversion applications.

A surface fluorination strategy to produce Zn anode for the 3D printable aqueous Zn batteries

Despite many performance merits (e.g., high theoretical capacity, suitable redox potential, high natural abundance), the application of Zn metal anode is compromised by severe parasitic reactions and Zn dendrite growth in aqueous electrolytes. Herein, we proposed a modified Zn foil with zinc fluoride (ZnF2) surface layer deposited by a simple fluorination process. Fast ion diffusion kinetics, low nucleation overpotential contributes to uniform nucleation sites and dendrite-free Zn deposition. Meanwhile, due to the block effect, detrimental side reactions are also effectively mitigated. As a result, ZnF2@Zn anode exhibits reversible Zn plating/stripping (700 h at 1 mA cm−2) with ultra-low voltage hysteresis (44 mV), leading to exceptional cycling stability over 300 cycles with 95.1 % capacity retention for the ZnF2@Zn/MnO2 full cell. In addition, we have also explored a separate process to produce 3D printable cathode to pair with the Zn anode for a Zn-ion battery. The exploring of 3D printing method is of great importance for the industrial level of manufacturing of batteries, which are the bridge to transfer electrode materials to devices. The printed cathode will be used to demonstrate the fast prototype process.

Flexible Si3C monolayer: A superior anode for high-performance non-lithium ion batteries

Due to the low cost, suitable redox potentials and intrinsic safety, non-lithium ion batteries (NLIBs) have attracted considerable attention in the next-generation energy storage systems; nonetheless, searching for efficient anodes is still a great challenge in the development of NLIBs. Herein, we systematically estimated the potential of emerging 2D Si3C as an anode of NLIBs by means of first-principles computations. Our results show that Na/K/Ca ions are stably adsorbed on the Si3C surface with adsorption energies of − 0.81 to − 0.17 eV. However, the positive adsorption energy implies Si3C is an inefficient anode for Mg/Al-ion batteries. During the metal ion intercalation, a semiconductor to metal transition is observed, suggesting that the Si3C anode could ensure superb conductivity for fast electronic transport. In addition, the metal ions diffuse rapidly on the Si3C surface with small energy barriers. Nonetheless, the presence of defects in Si3C severely degrades the ion mobility. Remarkably, the efficient accommodation of Na/K/Ca ions yields a high specific capacity of 1113.58, 835.18 and 2227.15 mA h g−1. The Si3C anode also possesses moderate mechanical stiffness and excellent structural flexibility, which are beneficial to achieve a favorable reversibility. All these results indicate that Si3C is a superior anode candidate for high-performance Na/K/Ca-ion batteries.

Hydrophilic silica spheres layer as ions shunt for enhanced Zn metal anode

Aqueous Zn ion batteries (AZIBs) have been widely studied due to their high safety, suitable redox potential and high theoretical capacity. As the most commonly used anode for AZIBs, Zn foil suffers from severe dendrites growth and undesired side reactions, causing battery failure. In this work, a coating layer of stacked SiO2 spheres is designed on a Zn metal surface (SiO2@Zn). The hydrophilic coating layer improves the electrolyte wettability of the Zn anode. Besides, it acts as ions shunt to lead Zn ions evenly plating between the coating layer and the metal anode, avoiding dendrites growth. With electrochemical characterizations and in-situ optical microscopy observations, the electrode presents a stable voltage profile and a long cycling life (2000 h at 0.5 mA cm−2), and the capacity decay in a full cell is significantly alleviated.

A Highly Reversible Zinc Anode for Rechargeable Aqueous Batteries.

Zinc metal holds a great potential as an anode material for next-generation aqueous batteries due to its suitable redox potential, high specific capacity, and low cost. However, the uncontrollable dendrite growth and detrimental side reactions with electrolytes hinder the practical application of this type of electrodes. To tackle the issues, an ultrathin (∼1 μm) sulfonated poly(ether ether ketone) (SPEEK) solid-electrolyte interphase (SEI) is constructed onto the Zn anode surface by a facile spin-coating method. We demonstrate that the polymeric SEI simultaneously blocks the water molecules and anions, uniformizes the ion flux, and facilitates the desolvation process of Zn2+ ions, thus effectively suppressing the side reactions and Zn dendrite formation. As a result, the newly developed Zn@SPEEK anode enables a symmetric cell to stably operate over 1000 cycles at 5 mA cm-2 without degradation. Moreover, with the Zn anode paired with a MnO2 cathode, the full cell exhibits an improved Coulombic efficiency (over 99% at 0.1 A g-1), a superior rate capability (127 mA h g-1 at 2 A g-1), and excellent cycling stability (capacity retention of 70% over 1000 cycles at 1 A g-1). This work provides a facile yet effective strategy to address the critical challenges in Zn anodes, paving the way for the development of high-performance rechargeable aqueous batteries.

Stoichiometric two-dimensional non-van der Waals AgCrS2 with superionic behaviour at room temperature.

Layered materials have attracted tremendous interest for accessing two-dimensional structures. Materials such as graphite or transition metal dichalcogenides, in which the layers are held together by van der Waals interactions, can be exfoliated through a variety of processes in a manner that retains the structure and composition of the monolayers, but this has proven difficult for solids with stronger interlayer interactions. Here, we demonstrate the exfoliation of AgCrS2, a member of the AMX2 family (where A is a monovalent metal, M is a trivalent metal and X is a chalcogen), through intercalation with tetraalkylammonium cations, chosen for their suitable redox potential. The as-exfoliated nanosheets consist of Ag layers sandwiched between two CrS2 layers, similar to their structure in the bulk. They show superionic behaviour at room temperature, with an ionic conductivity of 33.2 mS cm-1 at 298 K that originates from Ag+ ions rapidly hopping between neighbouring tetrahedral interstices; in the bulk, this behaviour is only observed above 673 K.

Electrochemical saturation of antimony-lead melts with oxygen: Cell design and measurement

Liquid metals have emerged as potential materials for fuel cell and battery applications due to their suitable redox potentials, fast redox kinetics, and/or active participation in electrode reactions. In this work, we study the electrochemical oxidation behavior of antimony-lead melts by the use of a robust, yttrium-stabilized zirconia based, test setup that can avoid the necessity for the use of precious metals as current collectors. Impedance spectroscopy results obtained at 700°C as a function of applied anodic polarization reveal the presence of two main contributions: an interfacial resistance, occurring at high-frequencies, related to the transference of oxygen-ions between the electrolyte and the anode melt and a low-frequency contribution, related to the diffusion of oxidized species within the bulk of the melt. These electrode mechanisms were followed as a function of the extent of melt oxidation, with suggested links made to the degree of melt segregation supported by SEM and XRD analyses.

Homogeneous Carbon/Potassium-Incorporation Strategy for Synthesizing Red Polymeric Carbon Nitride Capable of Near-Infrared Photocatalytic H2 Production.

The efficient utilization of near-infrared (NIR) light for photocatalytic hydrogen generation is vitally important to both solar hydrogen energy and hydrogen medicine, but remains a challenge at present, owing to the strict requirement of the semiconductor for high NIR responsiveness, narrow bandgap, and suitable redox potentials. Here, an NIR-active carbon/potassium-doped red polymeric carbon nitride (RPCN) is achieved for by using a similar-structure dopant as the melamine (C3 H6 N6 ) precursor with the solid KCl. The homogeneous and high incorporation of carbon and potassium remarkably narrows the bandgap of carbon nitride (1.7eV) and endows RPCN with a high NIR-photocatalytic activity for H2 evolution from water at the rate of 140 µmol h-1 g-1 under NIR irradiation (700 nm ≤ λ≤ 780nm), and the apparent quantum efficiency is high as 0.84% at 700 ± 10nm (and 13% at 500 ± 10nm). A proof-of-concept experiment on a tumor-bearing mouse model verifies RPCN as being capable of intratumoral NIR-photocatalytic hydrogen generation and simultaneous glutathione deprivation for safe and high-efficacy drug-free cancer therapy. The results shed light on designing efficient photocatalysts to capture the full spectrum of solar energy, and also pioneer a new pathway to develop NIR photocatalysts for hydrogen therapy of major diseases.

Self-assembly of carbon nanotubes on a hollow carbon polyhedron to enhance the potassium storage cycling stability of metal organic framework-derived metallic selenide anodes

Potassium-ion batteries (PIBs) is increasingly studied because of their suitable redox potential and high natural abundance. However, potential anode materials with long-term cycling stability are still in high demand because of the large radius of K+. Herein, an MOF-derived hierarchical carbon structure and the self-assembly of CNTs on hollow carbon polyhedrons are used as carbon matrices to disperse and stabilize metal selenides(Co-Se@CNNCP). When the hybrid is utilized in PIBs, it displays a specific capacity of 410 mA h g−1 at 0.1 A g−1 after 80 cycles and 253 mA h g−1 at 0.5 A g−1 after 200 cycles with a capacity retention of 100%, while the metal selenides dispersed on hollow carbon polyhedrons without CNTs (Zn-Co-Se@NCP) lose 86% of their capacity after 200 cycles. The superior cycling stability of the hybrid is mainly attributed to the large amounts of CNTs suppressing the agglomeration of the metal selenide nanoparticles on the surface, and the hollow carbon polyhedrons cause a high structural integrity during the repreated K+ insertion and extraction process. This work offers a feasible route to design a hierarchical carbon matrix for use as the anode materials of PIBs with long-term cycling stability.

Understanding the synergistic effect of Co-loading and B-doping in g-C3N4 for enhanced photocatalytic activity for overall solar water splitting

An effective approach of loading of metal (Co) and doping of non-metal (B) together has been considered to enhance the photocatalytic activity of tri-s-triazine based g-C3N4. Here, pristine and functionalized g-C3N4 with B-doping at bay C site (BC1–C3N4), corner C site (BC2–C3N4), Co-loading (Co–C3N4) and Co-loading and B-doping together [(Co–B)C1–C3N4 and (Co–B)C2–C3N4] have been studied for structural, electronic, optical and photocatalytic properties using hybrid density functional theory. B-doping in g-C3N4 formed p-type semiconductor while Co-loading revealed formation of n-type semiconductor with formation of Co-3d intermediate states while both together indicated partial charge compensation. All the functionalized films show lower overpotential value for oxygen evolution reaction (OER) as compared to g-C3N4 while for hydrogen evolution reaction (HER) lower overpotential values are obtained for Co–C3N4, (Co–B)C1–C3N4 and (Co–B)C2–C3N4. The present work, highlights the synergistic effects of Co-loading and B-doping in g-C3N4 in terms of formation of impurity states, high absorption, charge redistribution and lower OER and HER overpotential along with suitable redox potentials than g-C3N4 and suggests (Co–B)C1–C3N4 as potential candidate for overall photocatalytic water splitting.

Efficient Photogeneration of Hydrogen Boosted by Long-Lived Dye-Modified Ir(III) Photosensitizers and Polyoxometalate Catalyst

Efficient Photogeneration of Hydrogen Boosted by Long-Lived Dye-Modified Ir(III) Photosensitizers and Polyoxometalate Catalyst

The electronic and optical properties of Au decorated(1 0 [formula omitted] 4) dolomite surface: A first principles calculations

The electronic and optical properties before and after Au decoration on (101¯4) surface of dolomite were investigated based on first principles calculations. The electronic structure analysis indicates that the band gap decreases from 4.25 eV (pristine) to 0.81 eV (1 Au decorated case), and the work functions increase from 2.41 eV to 3.53 eV. The density of states analysis revealed that the band gap decrease is mainly attributed to the Au 5d doping states in the forbidden band gap. Moreover, an additional peak located at 310 nm of polarization direction on E//c appears after Au decoration, resulting in the increased absorption intensity in the ultraviolet and visible range. By comparing the redox potential with that of different kinds of pollution gas, it can be found that the Au decorated dolomite might be a good photocatalyst for NO removal. The above results indicate that the Au decorated dolomite could be used in visible light photocatalysis or photovoltaic applications due to its semiconductor characteristics and suitable redox potentials.

(Europe Section Alessandro Volta Medal Award) Electrolytes and Metallic Anodes: About an Old Argument That Marks the Fundamental Understanding of Modern Metal Anodes in Advanced Battery Systems

Simple, yet meaningful, experiments, already carried out in the 18th century by Galvani and Volta, are at the very base of modern batteries that shape our society. From the very first muscle twitch to batteries found nowadays in nearly every part of modern life, with the best known example of a modern battery represented by the lithium ion battery (LIB), the same basic principles are present. The comparably fast and seminal development of LIBs through assiduous collective efforts was granted the 2019 Nobel Prize in Chemistry.[1] Besides all modern perspectives, fundamental principles are still being derived from the early works of Volta and Galvani, which have not been always in agreement.Because the LIB technology is more and more approaching its ceiling in terms of specific energy (Wh kg−1) and energy density (Wh L−1) imposed by the nature of intercalation chemistry, metal-based anodes, such as Li, Na, Mg, Ca, Zn and Al, are currently considered for the next evolutional step of battery technology.[2,3,4] Independent of the chosen materials, the chemistry of the anodes (graphite, silicon or metal anodes) with the electrolyte plays a crucial role in the development of the batteries. In LIBs, the formation of a solid electrolyte interphase (SEI) on graphite in organic media induced by an external current/voltage and involving the reduction of the electrolyte components was key for the stable operation of such anodes.[5] Similar processes for metal-based anodes do not necessarily require electrode polarization conditions and can occur spontaneously. For example, supplementary to SEI formation on the Li surface, induced by the extremely low redox potential of metallic lithium (−3.04 V vs. SHE), other processes of Li deterioration, namely galvanic corrosion (worth also considering here: dendrite growth, volume changes of the Li anode, low Coulombic efficiency), have to be scrutinized. Recently, battery researchers revisited the corrosion phenomena in lithium metal batteries (LMBs).[6,7] A systematic study focused on the corrosion-related processes in model Li anodes (using Li powder) revealed the great significance that such processes exercise on the performance of LMBs.[7]From a different perspective, flammable non-aqueous electrolytes, widely used in the LIB/LMB systems, are causing increased safety concerns. As an alternative, Zn has been regarded as a potential anode material for aqueous batteries because of its high theoretical volumetric capacity and suitable redox potential (−0.76 V vs. SHE), along with an intrinsic safety from the aqueous electrolyte nature. Similar to the Li anode in nonaqueous electrolytes, the Zn anode has also long-standing challenges in conventional alkaline electrolytes, such as chemical instability (e.g. corrosion) and electrochemical irreversibility (e.g. non-uniform electrodeposition/-dissolution, dendrite growth).[8]In this perspective, the two worlds of Li-based and Zn-based battery systems are united and attributed to the lessons by Volta and Galvani. Metals from the Volta pile (Cu and Zn) and modern metals (Li) are discussed side by side and in correlation to each other. Solutions to address their challenges, and thus overcome the barriers of their application, in rechargeable systems will be highlighted. It is emphasized that the combination of metals (e.g. Li) with metal ions (e.g. Zn2+) can result in formation of intermetallic phases, able to improve stability of the electrodes under cell operation conditions. This can further result in an increase in safety and cycle life of the batteries utilizing metals as negative electrodes.[9] Special attention will be also given to the obstacles caused by the alkaline electrolytes with focus on the fundamental understanding of Zn reaction mechanisms. Approaches to overcome the challenges are presented and evaluated for their potential to facilitate further research and development of electrolytes in these systems.

Light-driven enzymatic nanosystem for highly selective production of formic acid from CO2

• Highly selective production of formic acid from CO 2 is achieved. • The simultaneous encapsulation of two enzymes in ZIF-8 improved reaction efficiency. • ZIF-8 provided a large amount of loaded protein with little damage to enzyme. • Efficient in situ regeneration of NADH was achieved by visible-light irradiation. • The designed nanosystem exhibited excellent operational stability and recyclability. Natural photosynthesis plays an important role in maintaining environmental carbon balance. Taking inspiration from this, we developed a light-driven, enzymatic nanosystem for the highly selective production of formic acid from CO 2 . The system combines photocatalytic graphitic carbon nitride (g-C 3 N 4 ) with two natural enzyme catalysts, carbonic anhydrase (CA) and formate dehydrogenase (FateDH), encapsulated in ZIF-8, a porous metal-organic framework (MOF). Efficient in situ regeneration of reduced nicotinamide adenine dinucleotide (NADH) is realized through visible-light irradiation of g-C 3 N 4 with a suitable redox potential (−0.3 V (NHE)). The introduction of ZIF-8 ensures a large amount of loaded protein with little damage to enzyme activity, and its encapsulation of CA and FateDH shortens the distance between the enzymes. This is conducive to increasing the diffusion of substances during the CO 2 -to-formic acid cascade reaction, thus improving the reaction efficiency. This work is expected to provide new insight into the design and development of highly selective, artificial photosynthesis systems to efficiently convert CO 2 into fuels, chemicals, and other materials.

Coarse-grained reduced MoxTi1−xNb2O7+y anodes for high-rate lithium-ion batteries

High-volumetric-energy-density lithium-ion batteries require anode material with a suitable redox potential, a small surface area, and facile kinetics at both single-particle and electrode level. Here a family of coarse-grained molybdenum substituted titanium niobium oxides MoxTi1−xNb2O7+y (single crystals with 1~2 μm size) underwent hydrogen reduction treatment to improve electronic conduction was synthesized, which is able to stably deliver a capacity of 158.5 mAh g−1 at 6,000 mA g−1 (65.2 % retention with respect to its capacity at 100 mA g−1) and 175 mAh g−1 (73 % capacity retention over 500 cycles) at 2,000 mA g−1, respectively. Via careful in situ electrochemical characterizations, we identified the kinetic bottleneck that limits their high-rate applications to be mainly ohmic loss at the electrode level (which mostly concerns electron transport in the composite electrodes) rather than non-ohmic loss (which mostly concerns Li+ lattice diffusion within individual particles). Such a kinetic problem was efficiently relieved by simple treatments of Mo substitution and gas-phase reduction, which enable full cells with high electrode density, and high volumetric energy/power densities. Our work highlights the importance of diagnosis, so that modifications could be made specifically to improve full-cell performance.

Density functional characterization of Bi-based photocatalysts: BiTaO4, Bi4Ta2O11 and Bi7Ta3O18

Using density-functional theory (DFT) calculations, we make a comparative study for the structural, electronic, and optical properties and photocatalysis of triclinic BiTaO4, orthorhombic BiTaO4, triclinic Bi4Ta2O11, and triclinic Bi7Ta3O18. We predict the photocatalytic capacity by analyzing the band edge position and light absorption. Besides, we calculate the effective masses of holes and electrons to compare the carriers’ mobility of the four bismuth tantalates. The optimized lattice parameters are obtained and crystal structures are analyzed. Electronic properties are studied by analyzing the band structures, partial density of state (PDOS), charge density, Mulliken population, and the hybridization intensity of Bi 6s-O 2p in the valence band maximum (VBM). Optical properties are investigated by calculating the optical absorption coefficient, optical refractive index, optical extinction coefficient, and dielectric function. By comparing the relative ratio of effective mass, we found that triclinic BiTaO4 and triclinic Bi7Ta3O18 not only have excellent mobility of carriers but also have excellent separation of photoexcited electron-hole pairs. Because of desirable mobility and separation of carriers, some absorption in visible light, and suitable redox potential, the four bismuth tantalates are predicted as promising catalyst candidates.