Oxygen vacancy mediated bismuth-based photocatalysts

Sunlight-driven photocatalysis,which can produce clean fuels and mitigate environmental pollution,has received extensive research attention due to its potential for addressing both energy shortages and environmental crises.Bismuth(Bi)-based photocatalysts with broad spectrum solar-light absorption and tunable structures,exhibit promising applications in solar-driven photocatalysis.Oxygen vacancy(OV)engineering is a widely recognized strategy that shows great potential for accelerating charge separation and small molecule activation.Based on OV engineering,this review focuses on Bi-based photocatalysts and provides a comprehensive overview including synthetic methods,regulation strategies,and applications in photocatalytic field.The synthetic methods of Bibased photocatalysts with OVs(BPOVs)are classified into hydrothermal,solvothermal,ultraviolet light reduction,calcination,chemical etching,and mechanical methods based on different reaction types,which provide the possibility for the structural regulation of BPOVs,including dimensional regulation,vacancy creation,elemental doping,and heterojunction fabrication.Furthermore,this review also highlights the photocatalytic applications of BPOVs,including CO_(2)reduction,N2 fixation,H2 generation,O_(2)evolution,pollutant degradation,cancer therapy,and bacteria inactivation.Finally,the conclusion and prospects toward the future development of BPOVs photocatalysts are presented.

Recent advances of bismuth-based electrocatalysts for CO_(2)reduction:Strategies,mechanism and applications

Electrocatalytic CO_(2)reduction reaction(CO_(2)RR),driven by clean electric energy such as solar and wind,can not only alleviate environmental greenhouse effect stemming from excessive CO_(2)emissions,but also realize the storage of renewable energy,for it guarantees the production of value-added chemicals and fuels.Among CO_(2)RR products,formic acid shows great advantages in low energy consumption and high added-value,and thus producing formic acid is generally considered as a profitable line for CO_(2)RR.Bismuth-based electrocatalysts exhibit high formic acid selectivity in CO_(2)RR.Herein,we review the recent progress in bismuth-based electrocatalysts for CO_(2)RR,including material synthesis,performance optimization/validation,and electrolyzers.The effects of morphologies,structure,and composition of bismuth-based electrocatalysts on CO_(2)RR performance are highlighted.Simultaneously,in situ spectroscopic characterization and DFT calculations for reaction mechanism of CO_(2)RR on Bi-based catalysts are emphasized.The applications and optimization of electrolyzers with high current density for CO_(2)RR are summarized.Finally,conclusions and future directions in this field are prospected.

Electronic modulation of two-dimensional bismuth-based nanosheets for electrocatalytic CO_(2) reduction to formate: A review

Electrocatalytic CO_(2) reduction reaction(eCO_(2) RR)has significant relevance to settle the global energy crisis and abnormal climate problem via mitigating the excess emission of waste CO_(2) and producing high-value-added chemicals.Currently,eCO_(2) RR to formic acid or formate is one of the most technologically and economically viable approaches to realize high-efficiency CO_(2) utilization,and the development of efficient electrocatalysts is very urgent to achieve efficient and stable catalytic performance.In this review,the recent advances for two-dimensional bismuth-based nanosheets(2D Bi-based NSs)electrocatalysts are concluded from both theoretical and experimental perspectives.Firstly,the preparation strategies of 2D Bi-based NSs in aspects to precisely control the thickness and uniformity are summarized.In addition,the electronic regulation strategies of 2D Bi-based NSs are highlighted to gain insight into the effects of the structure-property relationship on facilitating CO_(2) activation,improving product selectivity,and optimizing carrier transport dynamics.Finally,the considerable challenges and opportunities of 2D Bi-based NSs are discussed to lighten new directions for future research of eCO_(2) RR.

Crossover from Two-to Three-dimensional Superconducting States in Bismuth-based Cuprate Superconductor

To decipher the mechanism of high temperature superconductivity(SC),it is important to know how the superconducting pairing emerges from the unusual normal states of cuprate superconductors,including pseudogap,anomalous Fermi liquid and strange metal(SM).A long-standing issue under debate is how the superconducting pairing is formed and condensed in the SM phase because the superconducting transition temperature is the highest in this phase.

Regulating the crystal phase of bismuth-based semiconductors for promoted photocatalytic performance

Numerous bismuth-based semiconductors(BBSs)with sophisticated and desirable structures used as photocatalysts for efficient photocatalytic degradation of water organic contaminants have attracted considerable attention.However,regulating the crystal phases and phase transition of BBSs for promoted photocatalytic performance is ignored.Herein,the unique crystal structure and band structure features of each typical BBSs,and the vital roles on phase controlling of each phase were systematically presented based on the classification of BBSs.Notably,the critical factors for the phase transition of BBSs and intrinsic driving forces endowed by phases of BBSs for enhanced photocatalytic performance of organic contaminants removal were also elucidated.This review will provide systematical guidelines and horizons for regulating the crystal phase and phase transition of BBSs,promoting photocatalytic degradation and mineralization of organic contaminants.

Design and Synthesis of Bismuth-based Metal-Organic Frameworks for Photothermal Energy Conversion

Template effect of the solvents plays a key role in metal-organic frameworks (MOFs) synthesis.In addition,Bi3+ has a flexible and changeable coordination configuration,which is conducive to the construction of structurally diverse MOFs.Herein,we demonstrate that these features can be integrated into two stable bismuth-based porphyrin MOFs (named PFC-100 and PFC-101) with a wide range of light absorption.Further studies demonstrate that PFC-101 with weaker interactions of adjacent porphyrin planes achieves 22.2% photothermal conversion efficiency (PTCE);1.5-fold higher than that of PFC-100 (14.3%) under 660 nm irradiation.This study may shed light on the impact of solvent templates on the synthesis of bismuth-based MOFs,not only enriching the MOFs library but also broadening the horizon of their potential applications.

Advances in electrochemical reduction of carbon dioxide to formate over bismuth-based catalysts

Selective CO_(2) reduction to formate with highadded value is one of the most technologically and economically feasible pathways to realize electrochemical CO_(2) fixation. Bismuth-based catalysts have the advantages of nontoxicity, low cost, high abundance, as well as excellent stability. In addition, bismuth-based catalysts display excellent selectivity for the electrochemical reduction of CO_(2) to formate in aqueous electrolytes due to high-hydrogen evolution overpotential. Hence, bismuthbased catalysts are by far the most commercially available materials for electrochemical reduction of CO_(2) to formate.In this review, the electrochemical reduction of CO_(2) to formate over bismuth-based catalysts is elaborated. Firstly,this review describes performance evaluation indexes,evaluation systems and reaction mechanisms of the electrochemical reduction of CO_(2) to formate over bismuthbased catalysts. Subsequently, the research means to reveal the reaction mechanism of electrochemical reduction of CO_(2) to formate over bismuth-based catalysts and the performance improvement strategies of the reaction are described in detail. Finally, the opportunities and challenges in this encouraging field are discussed. We believe that this review will contribute to further development of electrochemical reduction of CO_(2) to formate over bismuthbased catalysts.

A comparative study of bismuth-based photocatalysts with titanium dioxide for perfluorooctanoic acid degradation

Bismuth-based material has been broadly studied due to their potential applications in various areas,especially used as promising photocatalysts for the removal of persistent organic pollutants(POPs) and several approaches have been adopted to tailor their features.Herein,the bismuth-based photocatalysts(BiOCl,BiPO4,BiOPO4/BiOCl) were synthesized by hydrothermal method and advanced characterization techniques(XRD,SEM,EDS elemental mapping,Raman and UV-vis DRS) were employed to analyze their morphology,crystal structure,and purity of the prepared photocatalysts.These synthesized photocatalysts offered a praiseworthy activity as compared to commercial TiO2(P25) for the degradation of model pollutant perfluorooctanoic acid(PFOA) under 254 nm UV light.It was interesting to observe that all synthesized photocatalysts show significant degradation of PFOA and their photocatalytic activity follows the order:bismuth-based catalysts> TiO2(P25)> without catalyst.Bismuth-based catalysts degraded the PFOA by almost 99.99% within 45 min while this degradation efficiency was 66.05% with TiO2 under the same reaction condition.Our work shows that the bismuth-based photocatalysts are promising in PFOA treatment.

Comparative investigation on amplifying performance between 980 nm and 1480 nm pumped bismuth-based EDFA

The population rate and power propagation equations are presented and solved to compare the amplification performances of bismuth-based Er3+-doped fiber amplifier (EDFA) pumped by 980-and 1480-nm lasers,respectively.In both single signal and coarse wavelength-division-multiplexing(CWDM)signals inputs,the 1480-nm pumped bismuth-based EDFA provides a larger signal gain than the 980-nm pumped one does,whereas the latter provides a relatively lower noise figure (NF).Comparative results indicate that the 1480-nm pumping scheme is more advantageous for bismuth-based EDFA regarding the band width and gain property.

Emerging Bismuth-Based Step-Scheme Heterojunction Photocatalysts for Energy and Environmental Applications

Photocatalysis has been expected to be a promising advanced oxidation process to endlessly convert exhaustless solar energy into storable,transportable,and usable chemical energy.As a kind of visible light-response semiconductors,Bi-based semiconductors can be developed into step-scheme(S-scheme)heterojunction photocatalysts,consisting of a reductive photocatalyst(RP)and an oxidative photocatalyst(OP)with band edge bending.This review sums up the state-of-the-art progress in Bi-based S-scheme heterojunctions,as well as the in-/ex-situ experiments and theoretical calculations to uncover the unique heterostructure and charge transfer mechanism of Bi-based S-scheme heterojunctions in depth.We can find that Bi-based S-scheme heterojunction photocatalysts have advantages in impeding the recombination of photo-induced electron-hole pairs,expediting the charge transfer,broadening solar energy utilization,and maximizing the potential energy of photo-redox reaction sites.Additionally,the recently published work on the potential applications of Bi-based S-scheme heterojunctions is also summarized,including photocatalytic H_(2) production,CO_(2) reduction with water,pollutant degradation,H_(2)O_(2) production,and N_(2) photofixation for ammonia and urea production by comparing and discussing their photocatalytic efficiency.On the basis of research progress,the immediate challenges and future perspectives of Bi-based S-scheme heterojunction photocatalysts are critically debated.

Solution-sol-gel-SHS process of quickly synthesizing bismuth-based superconductor precursor powder

A new process (solution-sol-gel-SHS,SSGS) based on the combination of the advantages of solution-sol-gel (SSG) process and solution self-propagating high-temperature synthesis (SHS) process has been developed to synthesize bismuth-based superconductor precursor powder.The new process consists of two main steps: (i) SSG process is used to prepare homogeneous wet gel;(ii) solution SHS process is carried out to transit wet gel to soft-agglomerated ultrafine (~0.3μm) precursor powder with low carbon content (<400×10-6).The new process has overcome many serious shortcomings of traditional SSG-processed powder such as hard agglomerate,coarse particles and high carbon content,and also greatly shortened the powder preparation period.The powder can be sintered into 110K 2223 superconductor with excellent quality in a short time.The process parameters to obtain homogeneous wet gel are optimized and SSG transition mechanism is also discussed.

Toward dendrite-free and anti-corrosion Zn anodes by regulating a bismuth-based energizer

Aqueous rechargeable zinc metal batteries display high theoretical capacity along with economical effectiveness,environmental benignity and high safety.However,dendritic growth and chemical corrosion at the Zn anodes limit their widespread applications.Here,we construct a Zn/Bi electrode via in-situ growth of a Bi-based energizer upon Zn metal surface using a replacement reaction.Experimental and theoretical calculations reveal that the Bi-based energizer composed of metallic Bi and ZnBi alloy contributes to Zn plating/stripping due to strong adsorption energy and fast ion transport rates.The resultant Zn/Bi electrode not only circumvents Zn dendrite growth but also improves Zn anode anti-corrosion performance.Specifically,the corrosion current of the Zn/Bi electrode is reduced by 90%compared to bare Zn.Impressively,an ultra-low overpotential of 12​mV and stable cycling for 4000​h are achieved in a Zn/Bi symmetric cell.A Zn–Cu/Bi asymmetric cell displays a cycle life of 1000 cycles,with an average Coulombic efficiency as high as 99.6%.In addition,an assembled Zn/Bi-activated carbon hybrid capacitor exhibits a stable life of more than 50,000 cycles,an energy density of 64​Wh kg−1,and a power density of 7​kW​kg−1.The capacity retention rate of a Zn/Bi–MnO_(2)full cell is improved by over 150%compared to a Zn–MnO_(2)cell without the Bi-based energizer.Our findings open a new arena for the industrialization of Zn metal batteries for large-scale energy storage applications.

Single-atom modified graphene cocatalyst for enhanced photocatalytic CO_(2) reduction on halide perovskite

Metal halide perovskite(MHP)has become one of the most promising materials for photocatalytic CO_(2) reduction owing to the wide light absorption range,negative conduction band position and high reduction ability.However,photoreduction of CO_(2) by MHP remains a challenge because of the slow charge separation and transfer.Herein,a cobalt single-atom modified nitrogen-doped graphene(Co-NG)cocatalyst is prepared for enhanced photocatalytic CO_(2) reduction of bismuth-based MHP Cs_(3)Bi_(2)Br_(9).The optimal Cs_(3)Bi_(2)Br_(9)/Co-NG composite exhibits the CO production rate of 123.16μmol g^(-1)h^(-1),which is 17.3 times higher than that of Cs_(3)Bi_(2)Br_(9).Moreover,the Cs_(3)Bi_(2)Br_(9)/Co-NG composite photocatalyst exhibits nearly 100% CO selectivity as well as impressive long-term stability.Charge carrier dynamic characterizations such as Kelvin probe force microscopy(KPFM),single-particle PL microscope and transient absorption(TA)spectroscopy demonstrate the vital role of Co-NG cocatalyst in accelerating the transfer and separation of photogenerated charges and improving photocatalytic performance.The reaction mechanism has been demonstrated by in situ diffuse reflectance infrared Fourier-transform spectroscopy measurement.In addition,in situ X-ray photoelectron spectroscopy test and theoretical calculation reveal the reaction reactive sites and reaction energy barriers,demonstrating that the introduction of Co-NG promotes the formation of ^(*)COOH intermediate,providing sufficient evidence for the highly selective generation of CO.This work provides an effective single-atom-based cocatalyst modification strategy for photocatalytic CO_(2) reduction and is expected to shed light on other photocatalytic applications.

Pt/Bi_(24)O_(31)Cl_(10) composite nanosheets with significantly enhanced photocatalytic activity under visible light irradiation

Efficient composite semiconductor photocatalysts are highly desirable for the visible-light-driven degradation of organic pollutants. In this study, Bi24O31Cl10 photocatalyst was prepared via a hydrothermal method and modified with Pt nanoparticles (NPs) through a facile deposition procedure. The composite photocatalyst was characterized by X-ray diffraction, transmission electronic microscopy, X-ray photoelectron spectroscopy, UV-vis diffusion reflectance spectroscopy, photoluminescence spectroscopy, and electron spin resonance. The 1.0 wt% Pt/Bi24O31Cl10 photocatalyst showed the highest activity for the degradation of methyl orange under visible light (source: 300 W Xe lamp coupled with a UV-cutoff filter), and the photocatalytic degradation efficiency improved about 2.2 times compared to that of pure Bi24O31Cl10. The composite photocatalyst could maintain most of its activity after four runs of the photocatalytic experimental cycle. This study could provide a novel insight for the modification of other desirable semiconductor materials to achieve high photocatalytic activities.

FORMATION MECHANISM OF MnBi PHASE IN Bi/MnBi EUTECTIC IN SITU COMPOSITE

Bi/MnBi eutectic in situ composite was produced by unidirectional solid-ification technique.The eutectic has a quasi-regular structure,in which the MnBi fi-bre is V-shaped in cross section and rod-like in longitudinal section,the aspect ratio isabout 300.The formation mechanism of this V-shaped MnBi phase was studied bycrystallographic analysis.The conclusion is that the(1120)face is the closest packedone while the(1010)face is the next.

Exploring centimeter-sized crystals of bismuth-iodide perovskite toward highly sensitive X-ray detection

Lead-halide perovskites exhibit outstanding performance in X-ray detection due to their intrinsic features such as high charge carrier mobility,large atomic number,and long carrier lifetime,but the toxicity of lead is regarded as the major factor hindering their development.Here,we introduce organic molecule(R)-(-)-2-methylpiperazine(R-MPz)into the bismuth-based structure to synthesize lead-free(R)-(H_(2)MPz)BiI_(5)(R-MBI).The high-quality centimeter-sized single crystals have been obtained,which show a low dark current and superior environmental stability.Particularly,the single-crystal device of R-MBI exhibits a highμτproduct up to 1.88×10^(-4)cm^(2)/V and a low trap density of 1.21×10^(10)cm^(-3).Further,the detector displays excellent detection sensitivity of 263.58μC Gy_(air)^(-1)cm^(-2)and a favorable low detection limit of 4.35μGyair/s,both of which meet the requirement for medical diagnostics.These findings shed light on the exploration of innovative bismuth-based hybrid perovskites for high-performance X-ray detection.

Synergistic injection of the thermosensitive hydrogel and Bi-based alloy bone cement for orthopaedic repair

Low-melting-point alloys have the advantages of good biocompatibility, plasticity, and near-bone mechanical strength, making them suitable as bone defect-filling materials for direct injection into defective bone sites. However, using low-melting-point alloys for orthopedic implants poses the challenge of causing thermal damage to the surrounding bone tissue during injection. In this study, a thermosensitive hydrogel is prepared and synergistically injected into the bone defect site with BiInSn. BiInSn solidifies and releases heat during injection, while the thermosensitive hydrogel absorbs heat and transforms into a gel state,encapsulating BiInSn. Therefore, the surrounding bone tissue is effectively protected from thermal damage. When BiInSn and the thermosensitive hydrogel were injected synergistically, in vitro thermal experiments revealed that the maximum temperature of the surrounding bone tissue reached 42℃. This temperature is below the 47℃ threshold, which causes permanent damage to bone tissues. In vivo experiments demonstrated that rats in the BiInSn-thermosensitive hydrogel group exhibited better recovery at the bone defect sites. These results suggest that the synergistic injection of Bi-based alloy and thermosensitive hydrogel is beneficial in reducing thermal damage to bone tissue, guiding bone tissue growth, and effectively facilitating the repair of bone defects.

Robust hybrid bismuth perovskites as potential photocatalysts for overall water splitting

Organic-inorganic hybrid perovskites have gained great attention as promising photocatalysts for hydrogen generation.However,due to their poor stability in water,the use of aqueous hydrohalic acid solutions is specifically required for an efficient hydrogen evolution.Herein,three novel photoactive lead-free hybrid perovskites based on bismuth and triazolium cations(denoted as IEF-15,IEF-16,and IEF-17(IEF stands for IMDEA energy frameworks))were synthesized and fully characterized(structural,compositional,optical,etc.).Further,these solids were proposed as photocatalysts for the challenging gas phase overall water splitting(OWS)reaction.Accordingly,IEF-16 thin films exhibited a remarkable photocatalytic activity in both H_(2) and O_(2) evolution,as a consequence of its appropriate bandgap and energy-band alignment,achieving hydrogen evolution rates ofμmol·g_(H_(2))^(-)1846 and 360 after 24 h under ultraviolet-visible(UV-vis)irradiation or simulated solar irradiation,respectively.This study additionally highlights the remarkable structural and photochemical stability of IEF-16 under different operational conditions(i.e.water volume,irradiation and temperature),paving the way for green hydrogen production from OWS using perovskite-based photocatalysts.

Tuning strategies and electrolyzer design for Bi-based nanomaterials towards efficient CO_(2)reduction to formic acid

The escalating emissions of greenhouse gases into atmosphere have precipitated a host of ecology and environ-mental concerns.Electrochemical reduction of CO_(2)(CO_(2)RR)is emerging as a sustainable solution for effectively addressing these issues.Leveraging the cost-effectiveness and eco-friendly attributes,Bi-based catalysts have been extensively studied with the purpose of enhancing activity and stability.This minireview majorly overviews the research advancements in Bi-based catalysts for CO_(2)electrocatalysis towards formic acid/formate production.Initially,we offer a concise overview of the reaction pathways involved in electrochemical CO_(2)reduction.Sub-sequently,we summarize the progress in various types of electrolysis cells and associated influencing factors.Specifically,the electronic structure modulation strategies of Bi-based catalysts including oxide-derived bismuth,bismuth-based chalcogenides,bimetallic and high-entropy compounds,etc.have been highlighted.Future research endeavors are poised to delve deeper into comprehending system dynamics during the reaction process to achieve exemplary stability high energy efficiency under industrial conditions.

In-situ construction of amorphous/crystalline contact Bi_(2)S_(3)/Bi_(4)O_(7) heterostructures for enhanced visible-light photocatalysis

Constructing a heterojunction photocatalyst is a significant method to enhance photocatalytic activity because it can promote the separation of photogene rated carriers.Herein,amorphous/crystalline contact Bi_(2)S_(3)/Bi_(4)0_(7) heterostructure was successfully synthesized by in-situ sulfidation of Bi407.The amorphous Bi_(2)S_(3) is diffused on the surface of Bi_(4)0_(7) rod,enhancing the visible light response and improving the transport of photogene rated carriers.Various characterizations confirm that the rapid separation of photogene rated carriers leads to increased photocatalytic performance.The optimized Bi_(2)S_(3)/Bi_(4)O_(7) heterostructure photocatalyst(BiS-0.15) exhibits the highest Cr(Ⅵ) reduction(0.01350 min^(-1)) and RhB oxidation(0.08011 min^(-1)) activity,which is much higher than that of pure Bi_(4)0_(7) and mixture under visible light irradiation.This work provides new insights into the construction of efficient novel photocatalysts.