Metal Ion Doping Research Articles

Cd-Doped Li4–xCdxTi5O12 (x = 0.20) as a High Rate Capable and Stable Anode Material for Lithium-Ion Batteries

Li4Ti5O12 (LTO), an excellent anode for lithium-ion batteries (LIBs), suffers from low electronic conductivity, limiting its high-power rate application. An aliovalent metal ion doping strategy that tunes the electronic/ionic conductivity can mitigate this issue. In this work, we investigated a series of Cd2+ dopings on the Li4–xCdxTi5O12 (x = 0, 0.05, 0.10, and 0.20) anode material by considering its effect on structural and electrochemical performance in Li- and Na-ion batteries. Combined Rietveld refinement and X-ray absorption spectroscopy (XAS) analysis explicitly identified Cd2+ doping into the Li(8a) tetrahedral site of the cubic spinel LTO structure. According to high-resolution powder diffraction (HRPD), scanning electron microscopy (SEM), 4-point probe, and X-ray photoelectron spectroscopy (XPS), an increase in Cd2+ doping from 5 to 20% at the Li (8a) site in the LTO results in a reduction in particle size, an expansion of lattice, an increase in conductivity, and an increase in Ti3+ content to Ti4+ ratio. High-resolution scanning transmission electron microscopy (HR-STEM) confirms that cadmium ions are interstitially doped in the LTO structure. Compared to the pristine LTO electrode in the Li half cell, the Li3.80Cd0.20Ti5O12 (Cd0.20-LTO) electrode showed a significant improvement in capacity at high rates and excellent cycling performance. The improvement in performance for Cd0.20-doped LTO is a consequence of the reduction in the diffusion path and the faster Li-ion kinetics. Therefore, this Cd-doped LTO series of electrodes demonstrates advantageous features for Li-ion battery systems.

Insights into the Efficiency Improvement for CZTSSe Solar Cells with over 12% Efficiency via Ga Incorporation

AbstractSuppressing the band tailing and nonradiative recombination caused by massive defects and defect clusters is crucial for mitigating open‐circuit voltage (Voc) deficit and improving the device performance of CZTSSe thin film solar cells. Cation substitution is one of the most commonly used strategies to address the above issues. The latest world record efficiency of 13.0% is obtained through this strategy (Ag substitution for Cu). Nevertheless, the importance of the approach to implementing metallic ion doping is easily overlooked by researchers. Here, different approaches are adopted to realize Ga doping and the differences in the efficacy and mechanism are thoroughly investigated. It is found that the secondary phase easily emerged when the physical‐based method is employed, and thus challenging to regulate the doping effect. In the case of the chemical‐based method, Ga doping can enlarge the depletion region widthand lower the defect activation energyand Urbach energy. Furthermore, GaSn defects located at grain boundaries can expand the energy band bending between GBs and grain interiors (GIs), thereby suppressing the deep defect states and nonradiative recombination. Consequently, power conversion efficiency as high as 12.12% with a Voc of 522 mV is achieved at 2% Ga doping.

Electronic structure and oxygen vacancy tuning of Co & Ni co-doped W18O49 nanourchins for efficient TEA gas sensing

Inducing oxygen vacancies in metal oxides by dual doping metal ions is the key to modulating their electronic structure and designing highly sensitive noble metal-free materials for detecting hazardous toxic gases. This study reports nickel (Ni) and cobalt (Co) co-doping in W18O49 crystal lattices leads to electronic structure modulation and generates oxygen vacancies to highly activate the redox capability and catalytic efficacy of the urchin-like W18O49 sensor toward triethylamine (TEA) gas species. The electronic structure modulations and physisorption interactions between TEA molecules and W18O49 and/or Co&Ni co-doped W18O49 nanourchins were calculated by density functional theory (DFT). The experimental results and DFT calculations confirmed more significant charge transfers due to bandgap excitation and reactivity of TEA with Co&Ni co-doped W18O49 verifying their strong binding interactions. Electrons move from lattice oxygen to surface O2 molecules through co-doped cations-induced oxygen vacancies, which provide active sites and form surface superoxide and peroxide species incorporated into the sensing materials surface. Benefiting from the high specific surface area, abundant active sites, and faster electron/charge transport capability, the optimized 2 %Ni-doped W18O49, and 1 %Co&2%Ni co-doped W18O49 nanourchins exhibited excellent sensitivity towards TEA gas molecules. The sensing response of Co&Ni-W18O49 (Ra/Rg = 156) is higher than Ni-W18O49 (Ra/Rg = 114) and W18O49 (Ra/Rg = 76) at 250 °C, fast response/recovery (16/13), and superior selectivity. The XRD and XPS results combining the DFT calculations verify the improved sensitivity due to the synergistic modulation of electronic structure, which paws a friendly strategy for enriching the free electronics to design cost-effective gas sensors.

Enhancement of Electrochemical Performance of Aqueous Zinc Ion Batteries by Structural and Interfacial Design of MnO2 Cathodes: The Metal Ion Doping and Introduction of Conducting Polymers

Aqueous zinc-ion batteries (AZIBs) and, in particular, Zn//MnO2 rechargeable batteries have attracted great attention due to the abundant natural resources of zinc and manganese, low cost, environmental friendliness, and high operating voltage. Among the various ways to improve the electrochemical performance of MnO2-based cathodes, the development of MnO2 cathodes doped with metal ions or composites of MnO2 with conducting polymers has shown such advantages as increasing the specific capacity and cycling stability. This mini-review focuses on the strategies to improve the electrochemical performance of manganese-based cathodes of AZIBs.

Cobalt-based zeolitic imidazole framework incorporated with well-dispersed bimetallic nanoparticles/ions as a multifunctional nanozyme for the degradation of environmental pollutants and discrimination of various phenolic substances

Several strategies, such as increasing catalytic active sites, doping another element, and designing hybrids, have been used to enhance the catalytic efficiency of the nanozyme for the efficient degradation of pollutants, sensitive analysis, and effective disease therapy. However, multifunctional nanozyme catalysts from a single MOF precursor with improved catalytic activity lack systematic research. Here, we have developed six nanozyme composites from a cobalt-based zeolitic imidazole framework (ZIF-67) as a precursor by doping metal ions (Ni2+ or Cu2+, or Fe2+) and subsequent high-temperature treatment. It is found that three kinds of metal ions-doped ZIF-67 and their corresponding high-temperature pyrolysis exhibit three kinds of catalytic activity including peroxidase-like, oxidase-like, and pollutant-reduced degradation nanozyme. Firstly, the degradation rate of pollutant substrates is increased by more than 13.3 times by doping metal ions (Ni2+ or Cu2+, or Fe2+) in ZIF-67. Moreover, a more than 96.3-fold enhancement is achieved by integrating doped-metal ions and pyrolysis of ZIF-67. Secondly, the oxidase-like activity of decorated-metal ions (Ni2+ or Cu2+, or Fe2+) ZIF-67 is enhanced by more than 300%. Thirdly, it is found that the reactive oxygen intermediate species (ROS) including singlet oxygen (1O2) and superoxide anion (•O2–) are produced by the oxidase-like reaction. Finally, we have proposed a facile and high-performance sensor array for colorimetric quantification and discrimination of nine phenolic pollutants and five biological molecules at no less than 2.0 μM by employing three decorated-metal ions ZIF-67 composite as the oxidase-like nanozyme. Ultimately, the colorimetric array sensor has great potential application prospects in monitoring environmental phenolic pollutants and disease diagnosis.

Enhanced Sonodynamic Cancer Therapy through Iron-Doping and Oxygen-Vacancy Engineering of Piezoelectric Bismuth Tungstate Nanosheets.

Sonodynamic therapy (SDT) is regarded as a new-rising strategy for cancer treatment with low invasiveness and high tissue penetration, but the scarcity of high-efficiency sonosensitizers has seriously hindered its application. Herein, the iron-doped and oxygen-deficient bismuth tungstate nanosheets (BWO-Fe NSs) with piezotronic effect are synthesized for enhanced SDT. Due to the existence of oxygen defects introduced through Fe doping, the bandgap of BWO-Fe is significantly narrowed so that BWO-Fe can be more easily activated by exogenous ultrasound (US). The oxygen defects acting as the electron traps inhibit the recombination of US-induced electrons and holes. More importantly, the dynamically renewed piezoelectric potential facilitates the migration of electrons and holes to opposite side and causes energy band bending, which further promotes the production of reactive oxygen species. Furthermore, Fe doping endows BWO-Fe with Fenton reactivity, which converts hydrogen peroxide (H2 O2 ) in tumor microenvironment into hydroxyl radicals (•OH), thereby amplifying the cellular oxidative damage and enhancing SDT. Both in vitro and in vivo experiments illustrate their high cytotoxicity and tumor suppression rate against refractory breast cancer in mice. This work may provide an alternative strategy to develop oxygen-deficient piezoelectric sonosensitizers for enhanced SDT via doping metal ions.

The complex heterogeneous Fenton reactivity of transition metal-doped ferrihydrite: Insight from the structural variation and pathway of H2O2 activation

Doping transition metal into ferrihydrite (Fh) may significantly affect its structure and Fenton reactivity. The comparative study of Fh and M(II)-Fh (M = Cu, Co, or Mn), for the first time, reveals that doping metal ions can alter the property and content of oxygen vacancy (OVs) and the oxidation potential of Fh, which subsequently affects H2O2 decomposition, HO. generation, and Fenton reactivity of the catalysts. The overall Fenton activity of the samples in decomposing bisphenol A decreases in the order Cu-Fh > Fh > Co-Fh > Mn-Fh. In specific, Cu-Fh is the most efficient catalyst as it has the lowest energy barrier for decomposing H2O2 into HO. at OVs sites and the highest oxidation potential (benefiting the reduction of Fe(III) to Fe(II) by H2O2). Our findings show the complex heterogeneous Fenton reactivity of M-Fh, and doping can be an efficient strategy for achieving highly efficient Fenton catalysts.

Probing the electrocatalytic activity of hierarchically mesoporous M-Co3O4 (M = Ni, Zn, and Mn) with branched pattern for oxygen evolution reaction

The large-scale production of hydrogen energy from the electrolysis of water requires earth-abundant and highly efficient oxygen evolution electrocatalysts. Cation substitution in spinel cobaltite is an efficient approach to tune electronic structure and improve their electrocatalytic activity towards oxygen evolution reaction (OER). In this article, for the first time, we have prepared hierarchically nanostructured Mn, Ni and Zn doped Co3O4 having a branching pattern via a simple hydrothermal and calcination method, and the same was used as an electrocatalyst for OER. Different methods confirmed the doping of transition metal ions. The result of structural characterization shows the formation of pure phase samples without impurity. The tetrahedral and octahedral functional groups were explained by FTIR spectroscopy, confirming the formation of a spinel structure. Ni-doped Co3O4 showed an excellent OER performance with a current density of 10 mA/cm2 at an overpotential of 380 mV in 1 M KOH and a Tafel slope of 63.19 mV/dec in alkaline media. The detailed study unveiled that the large surface area, hierarchically nanostructured branching pattern with porous structure, presence of a high amount of oxygen vacancy and the synergistic effect of Ni and Co are beneficial for increased OER activity and stability of Ni-Co3O4.

Mitigation of cation mixing of LiNiO2-based cathode materials by Li-doping for high-performing lithium-ion battery

Element doping of transition metal (TM) ions is commonly employed in the enhancement of structural and interfacial stability of layered nickel-rich cathode materials to construct high energy density lithium-ion batteries. However, one of the main factors for structural evolution and poor electrochemical stability of the layered nickel-rich cathode materials is the inherent Li+/Ni2+ disorder caused by dopants. To regulate the cation mixing, herein, the Li-doping is introduced into the TM slabs of the LiNiO2-based materials. Benefited from the charge compensation of the TM layers, the doped Li+ ions lead to the alleviation of the Li+/Ni2+ disorder generated during the synthesis stage and electrochemical charge/discharge cycles. It is demonstrated that proper amount of the doped Li+ ions would enhance the stability of the crystal lattice, improve the Li+ diffusion between electrode and electrolyte, and suppress the microcrack formation in the secondary grains of the materials. This is verified by the synergistic effect of Li/Mn co-doping, in particular, the LiNiO2-based layered material with 11 mol% Li and 1 mol% Mn exhibits great improvement in long-term cycling stability with capacity retention 71.11% after 200 cycles at 0.5C. The Li-doping strategy might provide a new perspective to the enhancement of structural stability of the layered nickel-rich materials for lithium-ion batteries in the future.

Effect of Na and Al doping on ZnO nanoparticles for potential application in sunscreens.

This study investigated the environment-friendly production and characterization of zinc oxide nanoparticles (ZnO NPs) doped with sodium (Na) and aluminum (Al) metals to decrease the photocatalytic activity of ZnO for use in sunscreen. The metal-doped zinc oxide (ZnO) materials were prepared by the microwave method using extracts of Averrhoa carambola, also known as star fruit, as a reducing agent. The effects of metal-ion doping on the crystal structure, morphology, and optical characteristics of ZnO were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDX), transmission electron microscopy (TEM), and ultraviolet-visible (UV-Vis) spectroscopy. The sun protection factor (SPF) of the sunscreen formulations containing undoped ZnO, Na-doped ZnO (Na/ZnO), and Al-doped ZnO (Al/ZnO) NPs were found to be 10.10, 25.10, and 43.08, respectively. Therefore, Na/ZnO and Al/ZnO showed increased SPF. Additionally, the prepared nanomaterials and sunscreens were effective against Gram-positive and Gram-negative bacteria and showed antioxidant activities. The methylene blue (MB) degradation was used to evaluate the photocatalytic activities of the undoped ZnO, Na/ZnO, and Al/ZnO NPs, which were found to be 66%, 46%, and 38%, respectively. Therefore, due to the structural defects of ZnO NPs, their photocatalytic activity was decreased with Na- and Al- doping. Additionally, Al/ZnO is an ideal candidate as an ingredient in sunscreens.

Microplasma and quenching-induced Co doped NiMoO4 nanorods with oxygen vacancies for electrochemical determination of glucose in food and serum

In this paper, Co-doped NiMoO4 nanorods with oxygen vacancies are synthesized on carbon cloth (Co-NiMoO4 NRs/CC) via microplasma and quenching-induced method.Owing to the surface defects and metal ion doping, the electronic structure and surface properties of the catalyst are tuned.Cyclic voltammetry (CV) and amperometry are used to investigate the electrocatalytic behavior of the glucose sensor in an alkaline medium with sensitivities of 7411 and 3125 μA L mmol−1 cm−2 in the linear range 1.0 μmol L–1 to 1.0 mmol L–1 and 1.0 mmol L–1 to 7.0 mmol L–1, respectively. The detection limit is 0.079 μmol L–1 at S/N = 3. Moreover, the as-prepared catalyst electrode is also successfully used in real food and serum samples, with a recovery rate of 97.1%-107.4%.The DFT calculations show that the Co site of the catalyst significantly influenced glucose sensing performance. This idea expands the application of quenching chemistry in electrochemical sensing.

Near-Infrared Emission from CdSe-Based Nanoplatelets Induced by Ytterbium Doping

Cadmium selenide (CdSe) nanoplatelets (NPLs) have attracted significant attention thanks to their favorable optical properties, including narrow emission linewidths, reduced Auger recombination, and a high absorption cross section. However, the photoluminescence (PL) quantum yield (QY) in the near-infrared (NIR) region is poor as compared to that in the visible region. Doping of metal ions is proven to be a successful strategy for inducing Stokes-shifted NIR emission. Here, we report the first account of the successful doping of ytterbium (Yb) into CdSe NPLs by a modified seeded-growth method. The successful incorporation of divalent Yb ions into CdSe NPLs resulted in an additional NIR emission apart from their excitonic emission. By optimizing the dopant concentration, we observed an impressive PL QY of ∼55% for these Yb-doped NPLs. Detailed elemental and optical characterizations were conducted to understand the emerging photophysical properties of these Yb-doped NPLs. These NIR-emitting lanthanide-doped CdSe NPLs might have applications in the next-generation bioimaging, night vision, and photodetection.

Structural and optical properties of Yttrium-Silver doped ZnO nanoparticle

Due to the fact that transition metal and rare earth ion doping may significantly alter and enhance the optical characteristics of II-VI semiconductor nanoparticles, these materials have recently attracted a lot of attention. Here, undoped and yttrium-silver doped zinc-oxide (x = 0.0,0.1,0.2) nanoparticles were successfully synthesized by the sol–gel method. The structural, morphological, and optical properties of Z(1-x)Y(x/2)Ag(x/2)O were examined. A well-arranged crystallite hexagonal structure was revealed by XRD patterns. The crystallite size for pure and doped ZnO observed by the Scherrer formula was less than 20 nm. The uniformly distributed, hexagonal-shaped particles were observed by FESEM. EDAX confirms the presence of Zn, Y, Ag, and O. UV analysis revealed that the band gap for pure ZnO is 5.11 eV, whereas the band gap for Y-Ag doped ZnO (0.1 and 0.2) is 4.96 and 5.04 eV, respectively.

Ni Ingress and Egress in SrTiO3 Single Crystals of Different Facets

Metal-ion surface interactions and/or doping in host perovskite-oxides are techniques that are widely employed for electronic structure tuning purposes and in developing novel heterogeneous catalysts; however, an in-depth understanding of the different elementary steps and factors involved in these processes is lacking. Herein, we use Atomic Force Microscopy (AFM), Scanning Transmission Electron Microscopy (STEM), and ab initio thermodynamics through density functional theory (DFT) to specifically investigate Ni surface adsorption, ingress, migration, segregation, and egress processes across different SrTiO3 (STO) single-crystal facets and terminations, specifically the (001), (110), and the (111). Under oxidizing and reducing conditions at different temperatures, Ni egress is observed on (110) STO samples, but not the (001). DFT results demonstrate Ni to have a higher thermodynamic egress propensity, specifically through an oxygen-terminated (110) facet in comparison to other (001) terminations, whereas for the (111)-Ti terminated facet, Ni is likely to remain in the bulk post ingress. We suggest that the observed uniqueness of the (110) surface facet toward Ni egress is possibly a consequence of a surface phase transition. These results can help guide design interests with regard to Ni surface stabilization, ingress/egress suppression, or facilitation in STO by elucidating the nuances involved across different facets.

Bandgap and defects regulation of La2−xAxNi1−yByO4+δ (A = K, Sr, B = Co, Mn) Ruddlesden-Popper type perovskites for efficient photocatalytic hydrogen evolution

The doping of certain exotic metal ions in photocatalysts may produce surface defects (such as oxygen vacancies) as well as bandgap changes, which may play an important role for their photocatalytic performance. In this work, bandgap modulation by precise control of defect concentration and transition metal oxidation state mainly owning to A-site doping and the B-site cations were achieved for the Ruddlesden-Popper structure (La2NiO4). The effects of K+, Sr2+, Co2+, Mn2+ single-mental doping and co-doping on the photocatalytic activity of La2NiO4 photocatalysts were investigated. It was found that the co-doping samples had a significant synergistic effect on the optical properties and photocatalytic activity of La2NiO4 photocatalysts. All the single-metal-doped La2NiO4 photocatalysts exhibited higher photocatalytic activity than their pristine counterpart. Moreover, the Sr2+, Co2+ co-doped La2NiO4 exhibited the best optical properties, photocatalytic activity and a the hydrogen production rate of La1.9Sr0.1Ni0.8Co0.2O4+δ more than 29 times of pure La2NiO4, has been achieved. Further analysis indicates that the surface oxygen vacancies as active sites promote efficient separation and migration of photogenerated carriers. The co-doped photocatalyst not only has a narrower bandgap, but also owns a more favorable conduction band position for photoinduced electron reduction. Overall, this work provides a simple method for introducing oxygen defects and bandgap modulation in Ruddlesden-Popper structure through metal ion doping. It is also expected to enlarge the understanding of the structure-dependence of the photocatalytic performance of perovskite materials.

Differences in the Oxidizing Species on the Surface of Metal-Doped Ferrihydrite and Hematite in the Alkaline S(IV)-O2 Solution

Although inorganic Fe(IV)═O oxo and Fe(III)-OOH peroxo have attracted more attention in aqueous environments, direct evidence for the characterization and identification of those oxidizing species is still lacking. In this study, the doped Cu/Co increases the reactivity of ferrihydrite/hematite in oxidizing As(III) by S(IV)-O2 under alkaline and dark conditions. Quenching experiments exclude the contributions of ·OH, O2•–, SO3•–, SO4•–, SO5•–, HSO5–, and H2O2 and confirm that peroxo and oxo are primary oxidizing species in As(III) oxidation. Electrochemical analyses indicate that Fe(IV)═O oxo and Fe(III)-OOH peroxo are primarily located on the surface of ferrihydrite and hematite. Selective oxidation of methyl phenyl sulfoxide and methyl phenyl sulfide to the corresponding oxidation products further reveals the presence of ≡Fe(IV)═O oxo on both ferrihydrite and hematite, and the doped Cu/Co significantly decreases the produced ≡Fe(IV)═O oxo on ferrihydrite, while increases the produced ≡Fe(IV)═O oxo on hematite. Meanwhile, selective oxidation of benzyl alcohol to benzaldehyde indicates the presence of ≡Fe(III)-OOH peroxo on both ferrihydrite and hematite, and the doped Cu/Co apparently increases the produced ≡Fe(III)-OOH peroxo on ferrihydrite and hematite. Raman analysis further reveals the presence of ≡Fe(IV)═O oxo and ≡Fe(III)-OOH peroxo on pure and metal-doped ferrihydrite/hematite, which also confirms that the doped Cu/Co decreases the produced ≡Fe(IV)═O oxo on ferrihydrite and increases ≡Fe(IV)═O oxo on hematite, while apparently increasing ≡Fe(III)-OOH peroxo on both ferrihydrite and hematite. This study enriches our understanding on the oxidizing species in the S(IV)-mediated oxidation processes under alkaline conditions, providing new insight on the oxidation reactivity of surface peroxo and oxo species mediated by the doped metal ions.

Synthesis of heteroatom incorporated porous carbon encapsulated Fe-doped Co9S8 as an efficient bifunctional electrocatalyst for overall water splitting

Doping metal ions into cobalt sulfide is a promising strategy to improve its performance as a cheap, green, highly active and sustainable electrocatalyst for overall water splitting. Herein, cauliflower-like, noble metal-free bifunctional electrocatalysts composed of S, N, and O atoms co-incorporated porous carbon (SNOPC) encapsulated Fe doped Co9S8 nanoparticles are successfully synthesized by direct pyrolysis of S, Co, and Fe-based polypyrrole (S–Co–Fe-PPYs) precursors for efficient overall water splitting. Specifically, the optimal catalyst (Fe0-33-Co9S8@SNOPC) shows excellent electrocatalytic performance in an alkaline electrolyte, requiring ultra-low overpotentials of 275 and 258 mV to reach a current density of 10 mA cm−2 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively, with exceptional stability for 50 h. Furthermore, when applied for overall water splitting as a bifunctional electrolyzer, it generates a current density of 10 mA cm−2 at an extremely low cell voltage of 1.595 V. The exceptional electrocatalytic activity of Fe0-33-Co9S8@SNOPC can be credited to the synergistic effect produced by Fe doped Co9S8 core and multi-atom incorporated porous carbon shell.

Impact of Y2O3 on structural, mechanical and nonlinear optical properties of CrO3-Na2O-B2O3 glasses

Herein, we investigate the effects of transition metal (Cr3+), alkali (Na1+), and rare earth (Y3+) ion doping on the structural, mechanical, and nonlinear optical properties of borate glass. The structural parameters revealed peculiar behaviors. The total ions concentrations values decreased from 2.13 × 1022 cm−3 for 0 mol% of Y2O3 to 2.04 × 1022 cm−3 for 5 mol% of Y2O3. The atomic packing density parameter (APD) values decreased from 67 % for 0 mol% of Y2O3 to 62 % for 5 mol% of Y2O3 additions. The mechanical parameters such as Young, shear, and bulk moduli showed decreased behaviors with further Y2O3 additions. The linear and nonlinear optical properties, such as refractive index, third-order nonlinear susceptibility, nonlinear refractive index, metallization criterion, average electronegativity, electronic polarizability, and optical basicity, were evaluated. The linear and nonlinear refractive indices showed increasing behaviors with further Y2O3 additions. These increased behaviors were attributed to the increased content of nonbridging oxygens with more Y2O3 additions. The present glasses have metallization criterion values between 0.377 and 0.387, which are optimal for use in nonlinear optical devices.

Metal-ion doping in metal-organic-frameworks: modulating the electronic structure and local coordination for enhanced oxygen evolution reaction activity.

The doping of metal-organic frameworks (MOFs) with metal-ions has emerged as a powerful strategy for enhancing their catalytic performance. Doping allows for the tailoring of the electronic structure and local coordination environment of MOFs, thus imparting on them unique properties and enhanced functionalities. This frontier article discusses the impact of metal-ion doping on the electronic structure and local coordination of MOFs, highlighting the effects on their electrocatalytic properties in relation to the oxygen evolution reaction (OER). The fundamental mechanisms underlying these modifications are explored, while recent advances, challenges, and prospects in the field are discussed. In addition, experimental techniques that can be applied to tackle the realization of effective metal-ion doping of MOFs are also noted briefly.

Factors influencing self-trapped exciton emission of low-dimensional metal halides

In this review, we mainly summarized the structure distortion, molecular engineering, electron–phonon coupling effect, external temperature and pressure, and metal ion doping that influence the self-trapped exciton emission of low-dimensional metal halides (LDMHs).