Bismuth Iodide Research Articles

Diethanolamine-functionalized BiOI hollow microspheres with negative conduction bands maximize the visible light photocatalytic performance for CO2 reduction

Bismuth iodide oxides have a wide range of applications as visible light photocatalysts in CO2 reduction reactions. While formation of heterostructures between semiconductors has been actively used to enhance catalytic reduction performance, the functional groups used to improve the separation ability of electron/holes (e-/h+) and surface energy band positions of BiOI surfaces have been rarely mentioned. Here, a new modification strategy was reported to improve the photocatalytic performance using solvents with hydroxyl functional groups to change the surface structure of BiOI hollow microspheres. Intriguingly, the BiOI hollow microspheres functionalized using diethanolamine have a larger negative surface conduction band than BiOI. Thus the photogenerated electron reduction capacity of the diethanolamine-functionalized BiOI is greatly enhanced, which can be obtained from the yield of reduction reaction testing and characterization results. This hydroxyl functional group modified BIOI provides a new strategy for improving photocatalytic performance. The DFT simulation provides a theoretical basis for photocatalytic CO2 reduction.

Lead‐Free All‐Inorganic Cesium Bismuth Iodide‐Based Perovskite Solar Cells: Recent Advances, Current Limitations, and Future Prospects

Remarkable achievements have been made in the development of perovskite solar cells (PSCs) with a rapidly boosting rate of power conversion efficiencies (PCEs) from 3.8% to 26.1%. Nevertheless, the toxicity of lead (Pb) elements and the hygroscopicity of organic cations in high‐efficiency PSCs severely hamper the commercialization of this technology. Consequently, Pb‐free all‐inorganic PSCs have received increasing attention recently to resolve the above‐mentioned toxicity and instability problems. Among various Pb‐free all‐inorganic halide perovskites, cesium bismuth iodide (CBI)‐based perovskites have gained particular attention as light absorbers in PSCs due to the tunable/small bandgaps, long carrier diffusion length/lifetime, and superb sunlight absorption coefficients. Nevertheless, the PCEs of CBI‐based PSCs are still far away from Pb‐based organic–inorganic counterparts because of the low structural dimensions and inferior perovskite film quality. Herein, the recent advances of CBI‐based perovskites as light‐absorbing materials in Pb‐free all‐inorganic PSCs are reviewed by emphasizing the distinct structural/optical/electronic properties and currently existing limitations. Additionally, several distinct strategies to boost the PCEs and robusticity of CBI‐based PSCs are presented. Finally, the unsolved key problems and future directions of CBI‐based PSCs are proposed, aiming to provide important insights for the further development of CBI‐based PSCs to realize sustainable, nontoxic, high‐performance perovskite photovoltaics.

Progress and applications of (Cu–)Ag–Bi–I semiconductors, and their derivatives, as next-generation lead-free materials for photovoltaics, detectors and memristors

The search for efficient but inexpensive photovoltaics over the past decade has been disrupted by the advent of lead-halide perovskite solar cells. Despite impressive rises in performance, the toxicity and stability concerns of these materials have prompted a broad, interdisciplinary community across the world to search for lead-free and stable alternatives. A set of such materials that have recently gained attention are semiconductors in the CuI–AgI–BiI3 phase space and their derivatives. These materials include ternary silver bismuth iodide compounds (Ag aBi bI a+3 b), ternary copper bismuth iodide Cu–Bi–I compounds and quaternary Cu–Ag–Bi–I materials, as well as analogues with Sb substituted into the Bi site and Br into the I site. These compounds are comprised of a cubic close-packed sub-lattice of I, with Ag and Bi occupying octahedral holes, while Cu occupies tetrahedral holes. The octahedral motifs adopted by these compounds are either spinel, CdCl2-type, or NaVO2-type. NaVO2-type Ag aBi bI a+3 b compounds are also known as rudorffites. Many of these compounds have thus far demonstrated improved stability and reduced toxicity compared to halide perovskites, along with stable bandgaps in the 1.6–1.9 eV range, making them highly promising for energy harvesting and detection applications. This review begins by discussing the progress in the development of these semiconductors over the past few years, focusing on their optoelectronic properties and process–property–structure relationships. Next, we discuss the progress in developing Ag–Bi–I and Cu–Bi–I compounds for solar cells, indoor photovoltaics, photodetectors, radiation detectors and memristors. We conclude with a discussion of the critical fundamental questions that need to be addressed to push this area forward, and how the learnings from the wider metal-halide semiconductor field can inform future directions.

Unveiling the origin of the efficient photocatalytic degradation of nitazoxanide over bismuth (oxy)iodide crystalline phases

The effect of the phase transition from bismuth iodide to bismuth oxyiodides on the photodegradation efficiency of nitazoxanide is explored.

Synthesis of different organic ammonium-based bismuth iodide perovskites for photodetection application.

Bismuth-based perovskites are promising candidates for highly stable halide perovskites with low toxicity. Here, we report the synthesis of a series of bismuth iodide-based perovskites with different primary, secondary, and tertiary ammonium cations and study their structural, thermal, and optical properties, and the likelihood of photodetection. Interestingly, the variation of A-site organic ammonium cations, with different interlayer spacings between adjacent bismuth iodide monolayers, has exotic effects on the diffraction patterns and morphological structures of the perovskite crystals. Thermogravimetric analysis reveals the highest thermal stability of tertiary ammonium-based bismuth perovskite with a decomposition temperature of 385 °C. The branched primary ammonium-based photodetector has photo-responsivity roughly two and four times faster than that of secondary and tertiary ammonium-based devices, respectively. These findings provide insight into the importance of A-site cation engineering for structural modulation and tailoring the optoelectronic properties of bismuth-based perovskites for emerging optoelectronic devices.

Quantum-confined bismuth iodide perovskite nanocrystals in mesoporous matrices.

Bismuth iodide perovskite nanocrystals are considered a viable alternative to the Pb halide ones due to their reduced toxicity and increased stability. However, it is still challenging to fabricate nanocrystals with a small and controlled size, and their electronic properties are not well understood. Here, we propose the growth of Bi iodide perovskite nanocrystals using different mesoporous silica with ordered pores of controlled diameter as templates. We obtain a series of confined Cs3Bi2I9 and MA3Bi2I9 perovskites with diameters of 2.3, 3.7, 7.4, and 9.2 nm, and precise size control. The complex absorption spectra of the encapsulated perovskites cannot be properly fitted using classical Tauc or Elliott formalisms. By fitting the spectra with a modified Elliott formula, the bandgap values and exciton binding energies (70-400 meV) could be extracted. The calculated bandgaps scale with the pore sizes. Using a combined experimental and theoretical approach, we demonstrate for the first time quantum confinement in 0D Bi-iodide perovskite nanocrystals.

Memristive properties and synaptic plasticity in substituted pyridinium iodobismuthates.

This study explores the impact of organic cations in bismuth iodide complexes on their memristive behavior in metal-insulator-metal (MIM) type thin-layer devices. The presence of electron-donating and electron withdrawing functional groups (-CN, -CH3, -NH2, and -N(CH3)2) on pyridinium cations induces morphological alterations in crystals, thus influencing the electronic or ionic conductivity of devices comprising sandwiched thin layers (thickness = 200 nm ± 50) between glass/ITO as bottom electrode (∼110 nm) and copper (∼80 nm) as the top electrode. It was found that the current-voltage (I-V) scans of the devices reveal characteristic pinched hysteresis loops, a distinct signature of memristors. The working voltage windows are significantly influenced by both the types of cation and the dimensionality of ionic fragments (0D or 1D) in the solid-state form. Additionally, the temperature alters the surface area of the I-V loops by affecting resistive switching mechanisms, corresponding log-log plots at three temperatures (-30 °C, room temperature and 150 °C) are fully studied. Given that a memristor can operate as a single synapse without the need for programming, aligning with the requirements of neuromorphic computing, the study investigates long-term depression, potentiation, and spike-time-dependent plasticity-a specific form of the Hebbian learning rule-to mimic biologically synaptic plasticity. Different polar pulses, such as triangle, sawtooth, and square waveforms were employed to generate Hebbian learning rules. The research demonstrates how the shape of the applied pulse series, achieved by overlapping pre- and post-pulses at different time scales, in association with the composition and dimensionality of ionic fragments, lead to changes in the synaptic weight percentages of the devices.

Bimetallic ternary Cobalt Bismuth Iodide for visible-light-drive N photocatalytic degradation of industrial dyes (TB)

In the water treatment process, sustainable, easy, effective and less expensive technique is always challenging and demanding. For this perspective, metal iodide shows great efficiency towards dye degradation processes. The present work explores the degradation of toluidine blue with the help of synthesized cobalt bismuth iodide (CBI). Structural and textural features show that on the sheet of bismuth iodide, tiny particles of cobalt iodide are uniformly distributed. The effect of various parameters such as – initial pH, dye concentration, amount of cobalt bismuth iodide and exposure of light intensity were examined. The experimental results indicate that cobalt bismuth iodide is having the advantage of the photodegradation process and is considered a significant new photocatalyst. The kinetics involved in the degradation was found to follow the pseudo-first-order kinetic model. At last, we discuss possible mechanisms for the mineralization of toludine blue. This study reveals a new choice for the potential application of cobalt bismuth iodide for the degradation of organic pollutants in water streams.

Fe- and S-Modified BiOI as Catalysts to Oxygen Evolution and Hydrogen Evolution Reactions in Overall Photoelectrochemical Water Splitting.

Developing catalysts with superior activity to hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is equally important to the overall photoelectrochemical water splitting to produce hydrogen. In this work, bismuth oxyiodide (BiOI), iron-modified bismuth iodide Fe/BiOI, and the sulfurized S-Fe/BiOI were prepared using the solvothermal method. The three materials all have good absorption ability for visible light. The photoelectrochemical catalytic activity of BiOI to oxygen evolution reaction (OER) is significantly enhanced after iron modification, while the sulfurized product S-Fe/BiOI exhibits better catalytic activity to hydrogen evolution reaction (HER). Hence, OER and HER can be simultaneously catalyzed by using Fe/BiOI and S-Fe/BiOI as anodic and cathodic catalysts to facilitate the overall photoelectrochemical water splitting process.

Halide Perovskites and Their Derivatives for Efficient, High-Resolution Direct Radiation Detection: Design Strategies and Applications.

The past decade has witnessed a rapid rise in the performance of optoelectronic devices based on lead-halide perovskites (LHPs). The large mobility-lifetime products and defect tolerance of these materials, essential for optoelectronics, also make them well-suited for radiation detectors, especially given the heavy elements present, which is essential for strong X-ray and γ-ray attenuation. Over the past decade, LHP thick films, wafers, and single crystals have given rise to direct radiation detectors that have outperformed incumbent technologies in terms of sensitivity (reported values up to 3.5×106 µC Gyair -1 cm-2 ), limit of detection (directly measured values down to 1.5 nGyair s-1 ), along with competitive energy and imaging resolution at room temperature. At the same time, lead-free perovskite-inspired materials (e.g., methylammonium bismuth iodide), which have underperformed in solar cells, have recently matched and, in some areas (e.g., in polarization stability), surpassed the performance of LHP detectors. These advances open up opportunities to achieve devices for safer medical imaging, as well as more effective non-invasive analysis for security, nuclear safety, or product inspection applications. Herein, the principles behind the rapid rises in performance of LHP and perovskite-inspired material detectors, and how their properties and performance link with critical applications in non-invasive diagnostics are discussed. The key strategies to engineer the performance of these materials, and the important challenges to overcome to commercialize these new technologies are also discussed.

Self-Powered Wide-Narrow Bandgap-Laminated Perovskite Photodetector with Bipolar Photoresponse for Secure Optical Communication.

Perovskite photodetectors with bipolar photoresponse characteristics are expected to be applied in the field of secure optical communication (SOC). However, how to realize the perovskite photodetector with bipolar response remains challenging. Herein, by introducing bismuth iodide (BiI3 ) into Sn-Pb mixed perovskite precursor solution, 2D perovskite FA3 Bi2 I9 is spontaneously formed at the bottom to realize a wide-narrow bandgap-laminated perovskite film. Wavelength-dependent bipolar response is realized based on the absorption difference of the photoactive region with different bandgap combined with the carrier competition of the homotypic transport layer adopted in the as-fabricated photodetector. Under the visible/near-infrared (NIR) light irradiation, the bottom/top of the film generates a higher carrier concentration, where electrons are easier to be separated and transported by the SnO2 /PC61 BM to the bottom/top electrodes, respectively, resulting in a negative and positive bipolar response. Finally, based on positive NIR signal as the effective signal and negative visible signal as the interference signal, the SOC system is realized, where the positive NIR signal is well hidden by the negative visible signal. This work provides a simple and feasible strategy for fabrication of laminated perovskite films to achieve bipolar response.

Fabrication of ambient processed carbon-based inorganic silver bismuth iodide solar cells without any expensive hole transport materials

Recently, tremendous progress has been made in inorganic–organic hybrid lead halide perovskite solar cells (PSCs). Still, most of the reported high-efficiency PSCs were made with harmful lead (Pb), which is one of the major obstacles to large-scale adoption. Silver bismuth iodide (AgBiI4) light absorbers have been identified as promising lead-free and low-toxic metal-halide materials for solar cell applications. Here, we present hole transport material (HTM) and lead-free carbon-based inorganic Rudorffite (AgBiI4) solar cells, which can be prepared by simple spin-coating using silver iodide and bismuth iodide precursors under ambient conditions. Powder X-ray diffraction (XRD), UV–visible absorption, and field emission scanning electron microscopy (FESEM) studies were used to characterize the deposited films. The performance of the fabricated device was studied using incident photon-to-current conversion efficiency (IPCE) and current density–voltage (J-V) characteristics. Electrochemical impedance spectroscopy (EIS) was used to investigate the charge transfer process at the interface of the fabricated device. Under standard illumination test conditions, the fabricated device showed a photoelectric conversion efficiency (PCE) of 1.04%. The devices also have good stability and retained 96% of their initial PCE after 200 hrs of storage in ambient conditions. This work demonstrates the potential of HTM-free, ambient processable, and lead-free Rudorffite stable solar cells.

Construction of bismuth oxide iodide (BiOI)/zinc titanium oxide (Zn2TiO4) p-n heterojunction nanofibers with abundant oxygen vacancies for improving photocatalytic carbon dioxide reduction

The conversion of carbon dioxide (CO2) into value-added syngas represents an effective approach for addressing both environmental issues and carbon neutrality issue. However, the slow charge dynamics and low CO2 affinity severely limit the photocatalytic CO2 reduction reaction. In this study, bismuth oxide iodide (BiOI)/zinc titanium oxide (Zn2TiO4) composite nanofibers were successfully prepared by immobilizing BiOI nanosheets on Zn2TiO4 electrospun nanofibers through a solvothermal reaction method. The results of photocatalytic research indicate that the BiOI/Zn2TiO4 composite nanofibers exhibit improved photocatalytic activity in CO2 reduction compared to pristine BiOI nanosheets and Zn2TiO4 nanofibers. The highest carbon monoxide (CO) release rate of BiOI/Zn2TiO4 nanofibers could reach 9.10 µmol‧g−1‧h−1, which is 18.6 times and 6.6 times higher than that of pristine BiOI nanosheets and Zn2TiO4 nanofibers, respectively. The enhanced photocatalytic activity can be credited to the formed BiOI/Zn2TiO4 p-n heterojunction, which can boost electron separation, reduce charge recombination at the interface, and promote the reaction process. The presence of oxygen vacancies in BiOI/Zn2TiO4 nanofibers can not only provide active site to facilitate the adsorption and activation of CO2 molecules, but also adjust the energy band structure of the catalyst to accelerate carriers transfer. After four cycles of testing, the CO release rate of BiOI/Zn2TiO4 nanofibers remains nearly constant, demonstrating its excellent stability. This work develops a feasible strategy to improve the efficiency of photoreduction of CO2 through energy band engineering and surface defect technology.

Exploring the synthesis, structure, and optoelectronic properties of lead-free halide perovskite Cs3Bi2I9 in single crystal and polycrystalline forms

In recent years, caesium bismuth iodide (Cs3Bi2I9), a lead (Pb)-free halide perovskite, has drawn more attention as a potential material than traditional semiconductor materials due to its lack of Pb toxicity and its outstanding stability against atmospheric air and moisture. Herein, the inverse temperature crystallization method is adopted to grow high-quality hexagonal-phase Cs3Bi2I9 perovskite single crystals. Furthermore, a Cs3Bi2I9 perovskite thin film is fabricated by a solution process using the two-step spin coating technique. A collective analysis of the structural properties, surface morphology, thermal stability, phase transition, and optoelectronic properties of these single crystal and polycrystalline thin films provides a comprehensive understanding and design strategy to develop environmentally stable, Pb-free, and high-performance photovoltaic and optoelectronic devices based on Cs3Bi2I9 perovskite. The findings of this study contribute to the advancement of perovskite-based technologies and pave the way for their successful integration into the renewable energy and optoelectronics industries.

Iodine vacancies enhanced C-Br bond activation and debromination of decabromodiphenyl ether over non-stoichiometric bismuth iodide homojunction

The activation of carbon-halogen bonds is of great significance to realize the breakdown of halogenated contaminants. Herein, a series of iodine vacancies enriched BiOI1-x photocatalysts prepared by simple temperature regulation were successfully applied in photocatalytic debromination of decabromodiphenyl ether (BDE209) under irradiation (λ > 360 nm). The obtained BiOI-450℃ composed of Bi7O9I3/Bi5O7I homojunction with iodine vacancies exhibited the best photocatalytic capacity to debromine BDE209. The removal of the first bromine atom from BDE209 on BiOI-450℃ displayed strong position selectivity that meta-debromination is superior to para-debromination, with essentially no ortho-debromination products formed. The selectivity of meta-debromination on iodine vacancies is as high as 72 %, which is higher than the selectivity on oxygen vacancies and sulfur vacancies. The larger space of iodine vacancy is more conducive to accommodating the bromine atom, therefore stabilizing the meta-bromine atomic adsorption configuration of BDE209 and promoting the C-Br bond activation by O…Br halogen bond with the support of surrounding oxygen atoms. This work will provide a feasible strategy for efficient dehalogenation of halogenated persistent organic pollutants based on halogenated bond activation.

Enhanced Circular Dichroism and Polarized Emission in an Achiral, Low Band Gap Bismuth Iodide Perovskite Derivative.

Lead halide perovskites and related main-group halogenido metalates offer unique semiconductor properties and diverse applications in photovoltaics, solid-state lighting, and photocatalysis. Recent advances in incorporating chiral organic cations have led to the emergence of chiral metal-halide semiconductors with intriguing properties, such as chiroptical activity and chirality-induced spin selectivity, enabling the generation and detection of circularly polarized light and spin-polarized electrons for applications in spintronics and quantum information. However, understanding the structural origin of chiroptical activity remains challenging due to macroscopic factors and experimental limitations. In this work, we present an achiral perovskite derivative [Cu2(pyz)3(MeCN)2][Bi3I11] (CuBiI; pyz = pyrazine; MeCN = acetonitrile), which exhibits remarkable circular dichroism (CD) attributed to the material's noncentrosymmetric nature. CuBiI features a unique structure as a poly-threaded iodido bismuthate, with [Bi3I11]2- chains threaded through a cationic two-dimensional coordination polymer. The material possesses a low, direct optical band gap of 1.70 eV. Notably, single crystals display both linear and circular optical activity with a large anisotropy factor of up to 0.16. Surprisingly, despite the absence of chiral building blocks, CuBiI exhibits a significant degree of circularly polarized photoluminescence, reaching 4.9%. This value is comparable to the results achieved by incorporating chiral organic molecules into perovskites, typically ranging from 3-10% at zero magnetic field. Our findings provide insights into the macroscopic origin of CD and offer design guidelines for the development of materials with high chiroptical activity.

Halide-guided active site exposure in bismuth electrocatalysts for selective CO2 conversion into formic acid

AbstractIt remains a challenge to identify the active sites of bismuth catalysts in the electrochemical CO2 reduction reaction. Here we show through in situ characterization that the activation of bismuth oxyhalide electrocatalysts to metallic bismuth is guided by the halides. In situ X-ray diffraction results show that bromide promotes the selective exposure of planar bismuth surfaces, whereas chloride and iodide result in more disordered active sites. Furthermore, we find that bromide-activated bismuth catalysts outperform the chloride and iodide counterparts, achieving high current density (>100 mA cm–2) and formic acid selectivity (>90%), suggesting that planar bismuth surfaces are more active for the electrochemical CO2 reduction reaction. In addition, in situ X-ray absorption spectroscopy measurements reveal that the reconstruction proceeds rapidly in chloride-activated bismuth and gradually when bromide is present, facilitating the formation of ordered planar surfaces. These findings show the pivotal role of halogens on selective facet exposure in activated bismuth-based electrocatalysts during the electrochemical CO2 reduction reaction.

Synthesis and characterization of mehtylammonium bismuth iodide via solvent engineering

Hybrid organic–inorganic halide perovskites (OIHPs) are an emerging class of photovoltaic materials that have gained tremendous attention in the field of optoelectronics. This work aims to investigate the characteristics of bismuth-based halide perovskite via solvent engineering for solar cell application. A bismuth-based organo-inorganic perovskite was synthesized and characterized for solar cell application via solvent engineering using Gamma Butyrolactone (GBL) as the based solvent and enhanced with Methylamine (MA) and acetonitrile (ACN). A solution processing facile method was adopted in the synthesis of the perovskite. The solvent engineering aims to tune its band gap and a remarkable band gap of 1.58eV which is within the range of an ideal band gap (1.5-1.6) required for solar cell application. The XRD micrograph exhibited several narrow sharp peaks which indicated crystallinity formation of the synthesized sample with 86% crystallinity. The FESEM/EDS micrograph indicated nature of the formed crystals and the chemical composition of the sample. A multilayer heptagonal crystal was observed. The TGA result showed that the sample is thermally stable at a temperature of 200oC before degradation occurred.

Influence of Anti-Solvents on the Performance of Cesium Bismuth Iodide Perovskite Solar Cells

In this paper, the influence of anti-solvents on the properties of cesium bismuth iodide (CBI – Cs3Bi2I9) perovskite solar cells (PeSCs) that were dripped with different anti-solvents, i.e., isopropanol, chlorobenzene (CB), and toluene during the spin-coating process was evaluated. Scanning electron microscopy images visually depicted the presence of extremely flat and homogeneous film with highly compactness for the Cs3Bi2I9 fabricated with isopropanol compared to other anti-solvents. A strong absorption band was observed at around the wavelength of 500 nm for all the CBI films, and we found that the maximum absorption percentage reached as high as 85%, while the current-voltage measurement showed that the CBI film fabricated with isopropanol showed twenty-one times increment than CB, in terms of power conversion efficiency and short circuit current density. Our findings suggest a further improvement of CBI film morphology by the anti-solvent for enhanced morphology and better solar cell performance in the future.

PH‐Dependent Synthesis of Pure‐Phase BiI3 and BiOI by Electrodeposition**

AbstractThis study reports the electrochemical synthesis of different morphologies of bismuth iodide and bismuth oxyiodide on graphite surfaces from acidic baths containing bismuth nitrate, sodium nitrate, iodine and ethylene glycol by a simple pH control. Linear sweep voltammetry analyses determined the potential window for the reduction of iodine where bismuth ions do not get reduced. The concentration of the iodide ions in the bath is regulated by the applied potential. At pH 0.2 and 0.5, bismuth is predominantly present as free Bi3+ ions, which react with iodide to form bismuth triiodide. On the other hand, even at slightly elevated pH 1.0 and 2.0, bismuth is predominantly complexed by water, nitrates and ethylene glycol. These complexes react with the iodide ions to form bismuth oxyiodide. Pure triiodide phase comprising polygonal platelets is obtained at pH 0.2. Pure oxyiodide phase comprising novel microflower‐like morphology formed from interlinked nano‐disks is obtained at pH 2.0.