Co-doped cryptomelane-type manganese oxide in situ grown on a nickel foam substrate for high humidity ozone decomposition.

Monolithic catalysts with excellent O3 catalytic decomposition performance were prepared by in situ loading of Co-doped KMn8O16 on the surface of nickel foam. The triple-layer structure with Co-doped KMn8O16/Ni6MnO8/Ni foam was grown spontaneously on the surface of nickel foam by tuning the molar ratio of KMnO4 to Co(NO3)2·6H2O precursors. Importantly, the formed Ni6MnO8 structure between KMn8O16 and nickel foam during in situ synthesis process effectively protected nickel foam from further etching, which significantly enhanced the reaction stability of catalyst. The optimum amount of Co doping in KMn8O16 was available when the molar ratio of Mn to Co species in the precursor solution was 2:1. And the Mn2Co1 catalyst had abundant oxygen vacancies and excellent hydrophobicity, thus creating outstanding O3 decomposition activity. The O3 conversion under dry conditions and relative humidity of 65%, 90% over a period of 5 hr was 100%, 94% and 80% with the space velocity of 28,000 hr-1, respectively. The in situ constructed Co-doped KMn8O16/Ni foam catalyst showed the advantages of low price and gradual applicability of the preparation process, which provided an opportunity for the design of monolithic catalyst for O3 catalytic decomposition.

Cradle to gate life-cycle assessment of battery grade nickel sulphate production through high-pressure acid leaching.

The rising global demand for high-purity nickel (Ni) sulphate, primarily used in lithium-ion batteries, is largely met by processing Indonesian laterite ores via hydrometallurgy. However, this supply chain is associated with significant environmental challenges and lack of transparent industrial data. This study uses a cradle-to-gate life cycle assessment (LCA) approach to quantify the greenhouse gas (GHG) emissions and energy use associated with the production of mixed hydroxide precipitate (MHP) from low-grade Indonesian laterites via high-pressure acid leaching (HPAL), which is then refined in China for the production of battery-grade nickel sulphate hexahydrate (NiSO4·6H2O, NSH). Fifteen impact categories are analyzed using established impact assessment and allocation (mass and economic) methods. The analysis reveals that feed preparation/HPAL and purification are the stages that contribute most to environmental impacts and in particular to global warming potential (GWP). Mass allocation results in higher environmental impacts, with 36.8 kg CO2-eq per 1 kg of Ni in NSH for GWP, compared to 33.8 kg CO2-eq per 1 kg of Ni in NSH when economic allocation is used. Sensitivity analysis shows a potential reduction (up to 13 %) in key impact categories if production of NSH is fully integrated in Indonesia or a greener electricity mix is used. Overall, our results indicate that the production of MHP in Indonesia and its refinement to NSH in China has a GWP about two times higher than the global average. Given the limited number of LCA studies for the production of battery-grade nickel, this study highlights major environmental concerns for the NSH production process from Indonesian laterites and identifies opportunities for improvement, towards a more sustainable global battery supply chain.

Stabilizing the Interphase in an Ultra-High-Nickel Cathode Enabling High-Performance Lithium-Ion Batteries.

High-nickel (Ni ≥ 90%) cathodes which have a high specific capacity hold great potential for next-generation lithium-ion batteries (LIBs). However, their practical application is restricted by their high interfacial reactivity because of the presence of residual lithium (Li) compounds on the surface. Herein, the LiNi0.9Co0.06Mn0.04O2 (NCM90) cathode is surface-modified with sulfur (S) via a simple and feasible dry mixing and low-temperature heat treatment, converting the residual lithium compound on the surface into inactive lithium sulfate (Li2SO4). This induces the formation of a stable inorganic enriched electrode-electrolyte interface on the cathode surface and inhibits the occurrence of side reactions, ultimately inhibiting lattice collapse and the dissolution of transition metal ions. After modifying, the capacity retention rates of NCM90/Li and NCM90/graphite cells are both greatly enhanced after long cycling. This work provides a new idea for the rational design of the electrode-electrolyte interface of high-nickel cathodes.

Preparation of 97% pure nickel-cobalt alloy from waste Ni-MH batteries by using waste glass as a fluxing agent.

With the e-waste growing rapidly all over the globe due to growing demand of electronics, smartphones, etc., coming up with an efficient and sustainable recycling process is the need of the hour. The present work reports a novel and sustainable process of manufacturing Ni alloy by bringing together three major waste streams such as waste Ni-MH batteries, e-waste plastics, and waste glass. The chosen temperature (1550 °C) favours the reduction of nickel-oxide by e-waste plastic as the reductant and sends rare earth elements present in the waste Ni-MH battery as oxide mixture to the slag phase. Waste glass powder used in this process functions as the fluxing agent, hence not requiring any additional flux. The reduction mechanism is gas-based, controlled mainly by hydrogen and carbon monoxide gases released as a result of decomposition of e-waste plastic as reaction commenced from cold zone (∼300 °C) to hot zone (1550 °C) in the horizontal tubular furnace. Formation of nickel alloy and enrichment of slag with mixture of rare earth oxides were confirmed by XRD, SEM-EDS, and Rietveld refining analysis performed on the XRD spectra of slag phase. ICP-OES (Inductively coupled plasma optical emission spectroscopy) and LIBS (laser induced breakdown spectrometer KT-100S) confirmed the high metal content in the alloy, thereby emphasizing the purity (∼98%) which is close to the composition of nickel super alloy. A maximum of 61% by weight REO enrichment was achieved in the slag phase, having La2O3:44.6%, Pr2O3:14.8%, and Nd2O3: 1.6% under optimised experimental conditions (1550 °C, 15 min, and 20% waste glass powder). This scientific investigation evinces a promising route for efficient utilisation of waste streams emanating from e-waste, thereby devising a sustainable recycling technique and protecting the environment, too.

In situ Construction of Hierarchical Ni-Co Hydroxides Derived from Metal-Organic Frameworks for High-Performance Ni-Zn Batteries.

Rechargeable nickel-zinc (Ni-Zn) batteries hold great promise for large-scale applications due to their relatively high voltage, cost-efficient zinc anode, and good safety. However, the commonly used cathode materials are susceptible to overcharging and experience irreversible capacity degradation, primarily as a result of low electrical conductivity and substantial limitations in volume-constrained proton diffusion. Here, we present a robust methodology for synthesizing hierarchical nickel-cobalt (Ni-Co) hydroxides characterized by hollow interiors and interconnected nanosheet shells with the help of in situ formed metal-organic frameworks (MOFs). The templating effect of the MOF induced the hierarchical structure, while the chemical etching of MOFs by Ni2+ ions resulted in a hollow structure, thereby enhancing the surface area. Theoretical calculations suggested that incorporation of cobalt reduces the band gap, thereby improving electronic conductivity, and lowered the deprotonation energy, which mitigated overcharge issues. These advantages conferred improved specific capacity, rate capability, and cyclic stability to the Ni-Co hydroxide. The Ni-Zn cell delivered specific energy values of 338 Wh kg-1 at 1.62 kW kg-1 and 142 Wh kg-1 at 29.89 kW kg-1. Our investigations undercoreed the critical role of MOFs as intermediates in the preparation of multi-component hydroxide and the construction of hiearchical structures to achieve superior performance.

Copper dual-doping strategy of porous carbon nanofibers and nickel fluoride nanorods as bi-functional oxygen electrocatalysis for effective zinc-air batteries.

Designing and developing efficient, low-cost bi-functional oxygen electrocatalysts is essential for effective zinc-air batteries. In this study, we propose a copper dual-doping strategy, which involves doping both porous carbon nanofibers (PCNFs) and nickel fluoride nanoparticles with copper alone, successfully preparing copper-doped nickel fluoride (NiF2) nanorods and copper nanoparticles co-modified PCNFs (Cu@NiF2/Cu-PCNFs) as an efficient bi-functional oxygen electrocatalyst. When copper is doped into the PCNFs in the form of metallic nanoparticles, the doped elemental copper can improve the electronic conductivity of composite materials to accelerate electron conduction. Meanwhile, the copper doping for NiF2 can significantly promote the transformation of nickel fluoride nanoparticles into nanorod structures, thus increasing the electrochemical active surface area and enhancing mass diffusion. The Cu-doped NiF2 nanorods also possess an optimized electronic structure, including a more negative d-band center, smaller bandgap width and lower reaction energy barrier. Under the synergistic effect of these advantages, the obtained Cu@NiF2/Cu-PCNFs exhibit outstanding bi-functional catalytic performances, with a low overpotential of 0.68 V and a peak power density of 222 mW cm-2 in zinc-air batteries (ZABs) and stable cycling for 800 h. This work proposes a one-step way based on the dual-doping strategy, providing important guidance for designing and developing efficient catalysts with well-designed architectures for high-performance ZABs.

Oxalate-derived porous C-doped NiO with amorphous-crystalline heterophase for supercapacitors.

Constructing amorphous/crystalline heterophase structure with high porosity is a promising strategy to effectively tailor the physicochemical properties of electrode materials and further improve the electrochemical performance of supercapacitors. Here, the porous C-doped NiO (C-NiO) with amorphous/crystalline heterophase grown on NF was prepared using NF as Ni source via a self-sacrificial template method. Calcining the self-sacrificial NiC2O4 template at a suitable temperature (400 °C) was beneficial to the formation of porous heterophase structure with abundant cavities and cracks, resulting in high electrical conductivity and rich ion/electron-transport channels. The density functional theory (DFT) calculations further verified that in-situ C-doping could modulate the electronic structure and enhance the OH- adsorption capability. The unique porous amorphous/crystalline heterophase structure greatly accelerated electrons/ions transfer and Faradaic reaction kinetic, which effectively improved the charge storage. The C-NiO calcined at 400 °C (C-NiO(400)) displayed a markedly enhanced specific charge, outstanding rate property and excellent cycling stability. Furthermore, the hybrid supercapacitor assembled by C-NiO(400) and active carbon achieved a high energy density of 49.0 Wh kg-1 at 800 W kg-1 and excellent cycle stability (90.9 % retention at 5 A/g after 10 000 cycles). This work provided a new strategy for designing amorphous/crystalline heterophase electrode materials in high-performance energy storage.

Interface Engineering by Unsubstituted Pristine Nickel Phthalocyanine as Hole Transport Material for Efficient and Stable Perovskite Solar Cells.

Lead halide perovskite solar cells (PSCs) have been rapidly developed in the past decade. With the development of a PSC, interface engineering plays an increasingly important role in maximizing device performance and long-term stability. We report a simple and effective interface engineering method for achieving improvement of PSCs up to 20% by employing unsubstituted pristine nickel phthalocyanine (NiPc). Thermal annealing of NiPc improves the interface between NiPc and perovskite because of the incorporation of NiPc molecules into the perovskite grain boundaries, which creates improvements in hole extraction from the perovskite absorber layer, as evidenced by time-resolved photoluminescence measurements. This significantly improves the charge transfer and collection efficiency, which are closely related to the improvement of the interface between perovskite and NiPc.

Simultaneously Boosting Direct and Indirect Urea Oxidation of Nickel Hydroxide via Strategic Yttrium Doping.

Urea electrolysis can address pressing environmental concerns caused by urea-containing wastewater while realizing energy-saving hydrogen production. Highly efficient and affordable electrocatalysts are indispensable for realizing the great potential of this emerging technology. Among the numerous candidates, α-Ni(OH)2 has the merits of good electrocatalytic activity, adjustable heteroelement doping, and low cost; consequently, it has received tremendous attention in the electrolytic fields. Herein, a Y3+-doping strategy is developed to effectively enhance the catalytic performance of nickel hydroxide in the urea oxidation reaction (UOR). Our results show that Y3+ incorporation successfully modulates the electronic structure of α-Ni(OH)2 by inducing Ni3+ formation in the crystal lattice to initiate direct UOR, facilitates the Ni3+/Ni2+ redox transition with higher current responses to promote indirect UOR, and maintains the structural stability of YNi-10 (Ni2+/Y3+ molar ratio = 1:0.1) during long-term UOR operation. Owing to these features, the obtained YNi-10 sample exhibits a higher current density (127 vs 79 mA cm-2 at 1.5 V), a lower Tafel slope (48 vs 75 mV dec-1), a larger potential difference between the UOR and oxygen evolution reaction (OER, 0.26 vs 0.22 V at 80 mA cm-2), a higher reaction rate constant (1.1 × 105 vs 3.1 × 103 cm3 mol-1 s-1), and a reduced activation energy of UOR (2.9 vs 14.8 kJ mol-1) compared with the Y-free counterpart (YNi-0). This study presents a promising strategy to simultaneously boost direct and indirect UORs, providing new insights for further developing high-performance electrocatalysts.

Di-chloridotetra-kis-(3-meth-oxy-aniline)nickel(II).

The reaction of nickel(II) chloride with 3-meth-oxy-aniline yielded di-chlorido-tetra-kis-(3-meth-oxy-aniline)nickel(II), [NiCl2(C7H9NO)4], as yellow crystals. The NiII ion is pseudo-octa-hedral with the chloride ions trans to each other. The four 3-meth-oxy-aniline ligands differ primarily due to different conformations about the Ni-N bond, which also affect the hydrogen bonding. Inter-molecular N-H⋯ Cl hydrogen bonds and short Cl⋯Cl contacts between mol-ecules link them into chains parallel to the b axis.

Bis[µ-3-(pyridin-2-yl)pyrazolato]bis-[acetato-(3,5-dimethyl-1H-pyrazole)-nickel(II)].

The title compound, [Ni2(C8H6N3)2(C2H3O2)2(C5H8N2)2] or [Ni(µ-OOCCH3)(2-PyPz)(Me2PzH)]2 (1) [2-PyPz = 3-(pyridin-2-yl) pyrazole; Me2PzH = 3,5-dimethyl pyrazole] was synthesized from Ni(OOCCH3)2·4H2O, 2-PyPzH, Me2PzH and tri-ethyl-amine as a base. Compound 1 {[Ni2(C30H34N10Ni2O4)]} at 100 K has monoclinic (P21/n) symmetry and the mol-ecules have crystallographic inversion symmetry. Mol-ecules of 1 comprise an almost planar dinuclear NiII core with an N4O2 coordination environment. The equatorial plane consists of N3,O coordination derived from one of the bidentate acetate O atoms and three of the N atoms of the chelating 2-PyPz ligand while the axial positions are occupied by neutral Me2PzH and the second O atom of the acetate unit. The Ni atoms are bridged by the nitro-gen atom of a deprotonated 2-PyPz ligand. Compound 1 exhibits various inter- and intra-molecular C-H⋯O and N-H⋯O hydrogen bonds.

Surface-Engineered Ni2P: An Efficient Oxygen Electrocatalyst for Zinc-Air Battery.

The surface engineering of electrocatalysts is one of the promising strategies to increase the intrinsic activity of electrocatalysts. It generates anion/cation vacancy defects and increases the electrochemically active surface area. We describe the surface engineering of Ni2P to favorably tune the bifunctional oxygen electrocatalytic activity and the development of a rechargeable zinc-air battery (ZAB). Ni2P encapsulated with N and P-dual doped carbon (Ni2P@NPC) is synthesized using a single-source precursor complex tris-(2,2'-bipyridine)nickel(II) bis(hexafluorophosphate). The surface engineering of the as-synthesized Ni2P@NPC is achieved by the controlled acid treatment at room temperature. The surface engineering removes carbon debris and opens the pores, exfoliates the encapsulating carbon layer, increases the P-vacancy in the crystal lattice, and boosts the electrochemically active surface area. The surface-engineered catalyst exhibits enhanced bifunctional activity towards oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The electrocatalytically active sites of engineered catalysts are highly accessible for facilitated electron transfer kinetics. P-vacancy favors the facile formation of defect-rich OER active metal oxyhydroxide species. The rechargeable ZAB based on the engineered catalyst delivers a specific capacity of 770.25 mA h gZn-1, energy density of 692 Wh kgZn-1, and excellent charge-discharge cycling performance with negligible voltaic efficiency loss (0.6 %) after 100 h.

In situ Synchrotron X-ray Metrology Boosted by Automated Data Analysis for Real-time Monitoring of Cathode Calcination.

Synchrotron X-ray-based in situ metrology is advantageous for monitoring the synthesis of battery materials, offering high throughput, high spatial and temporal resolution, and chemical sensitivity. However, the rapid generation of massive data poses a challenge to on-site, on-the-fly analysis needed for real-time process monitoring. Here, a weighted lagged cross-correlation (WLCC) similarity approach is presented for automated data analysis, which merges with in situ synchrotron X-ray diffraction metrology to monitor the calcination process of the archetypal nickel-based cathode, LiNiO2. The WLCC approach, incorporating variables that account for peak shifts and width changes associated with structural transformations, enables rapid extraction of phase progression within 10 seconds from tens of diffraction patterns. Details are captured, from initial precursors to intermediates and the final layered LiNiO2, providing information for agile on-site adjustments during experiments and complementing post hoc diffraction analysis by offering insights into early-stage phase nucleation and growth. Expanding this data-powered platform paves the way for real time calcination process monitoring and control, which is pivotal to quality control in battery cathode manufacturing.

Asymmetric Catalytic Synthesis of Allylic Sulfenamides from Vinyl α-Diazo Compounds by a Rearrangement Route.

The asymmetric rearrangement of allylic sulfilimines is an effective route to synthetic attractive targets such as allylic sulfenamides and others. The current methods are limited to chirality transfer from chiral allylic sulfilimine precursors. Herein, we report a general and fundamentally new rearrangement route accessing optically enriched allylic sulfenamides and their derivatives. The process involves a S-alkylation and an unusual S-to-N rearrangement step. The chiral nickel complex enables the transformation of a broad scope of sulfenamides and vinyl α-diazo pyrazoleamides under mild conditions. Various allylic sulfenamides have been synthesized with excellent γ-regioselectivity and enantioselectivity, which can be efficiently converted to sulfinamide and 4-aminobutenoic acid derivatives. In addition, DFT calculations demonstrate the connection between the spin state and conformation of nickel vinyl carbenoid, as well as an unknown rearrangement process.

Oxyanion-Sensitive Catalytic Activity of Ni(II)/Oxyanion Systems for Heterogeneous Organic Degradation: Differential Oxidizing Capacity of Ni(III) and Ni(IV) as High-Valent Intermediates.

This study demonstrated that NiO and Ni(OH)2 as Ni(II) catalysts exhibited significant activity for organic oxidation in the presence of various oxyanions, such as hypochlorous acid (HOCl), peroxymonosulfate (PMS), and peroxydisulfate (PDS), which markedly contrasted with Co-based counterparts exclusively activating PMS to yield sulfate radicals. The oxidizing capacity of the Ni catalyst/oxyanion varied depending on the oxyanion type. Ni catalyst/PMS (or HOCl) degraded a broad spectrum of organics, whereas PDS enabled selective phenol oxidation. This stemmed from the differential reactivity of two high-valent Ni intermediates, Ni(III) and Ni(IV). A high similarity with Ni(III)OOH in a substrate-specific reactivity indicated the role of Ni(III) as the primary oxidant of Ni-activated PDS. With the minor progress of redox reactions with radical probes and multiple spectroscopic evidence on moderate Ni(III) accumulation, the significant elimination of non-phenolic contaminants by NiOOH/PMS (or HOCl) suggested the involvement of Ni(IV) in the substrate-insensitive treatment capability of Ni catalyst/PMS (or HOCl). Since the electron-transfer oxidation of organics by high-valent Ni species involved Ni(II) regeneration, the loss of the treatment efficiency of Ni/oxyanion was marginal over multiple catalytic cycles.

Reduced representation bisulfite sequencing (RRBS) analysis reveals variation in distribution and levels of DNA methylation in white birch (Betula papyrifera) exposed to nickel.

Research in understanding the role of genetics and epigenetics in plant adaptations to environmental stressors such as metals is still in its infancy. The objective of the present study is to assess the effect of nickel on DNA methylation level and distribution in white birch (Betula papyrifera Marshall) using reduced representation bisulfite sequencing (RRBS). The distribution of methylated C sites of each sample revealed that the level of methylation was much higher in CG context varying between 54% and 65%, followed by CHG (24%-31.5%), and then CHH with the methylation rate between 3.3% and 5.2%. The analysis of differentially methylated regions (DMR) revealed that nickel induced both hypermethylation and hypomethylation when compared to water. Detailed analysis showed for the first time that nickel induced a higher level of hypermethylation compared to controls, while potassium triggers a higher level of hypomethylation compared to nickel. Surprisingly, the analysis of the distribution of DMRs revealed that 38%-42% were located in gene bodies, 20%-24% in exon, 19%-20% in intron, 16%-17% in promoters, and 0.03%-0.04% in transcription start site. RRBS was successful in detecting and mapping DMR in plants exposed to nickel.

Co-based metal-organic frameworks for enhanced nickel adsorption and its impact on nitrifying microbial activity.

The release of nickel "Ni(II)" into aquatic environments is of great concern because of environmental and health issues. Metal-organic frameworks (MOFs) are one of the most promising technologies for removing heavy metals from water. In this work, an octahedral Co-based MOF (Co-MOF) was synthesized with a high Ni(II) removal capacity (qmax of 1534.09 ± 45.49 mg g-1) in aqueous media. For the first time, the effect of Co-MOF alone and in co-exposure with Ni(II) on nitrifying microbial consortium was assessed using dynamic microrespirometry. A single concentration of Co-MOF had no significant effects on nitrifying microbial consortium, while the concentration of Ni(II) exerted non-competitive inhibition on the nitrifying microbial consortium with an IC50 of 1.67 ± 0.03 mg L-1. In addition, the theoretical speciation analysis showed a decrease of 40% of IC50 when the free Ni(II) concentration was considered. Co-exposure of Co-MOF and Ni(II) during the nitrifying process allowed us to conclude that Co-MOF is an effective adsorbent for Ni(II) and can be used to mitigate the inhibitory effects of nickel on nitrifying microbial consortia, which is crucial for maintaining the good operation of wastewater treatment and balance of nitrogen cycle.

Associations between blood nickel and lung function in young Chinese: An observational study combining epidemiology and metabolomics.

Prior research has explored the relationship between occupational exposure to nickel and lung function. Nonetheless, there is limited research examining the correlation between blood nickel levels and lung function among young adults in the general population. The metabolomic changes associated with nickel exposure have not been well elucidated. On August 23, 2019, we enrolled 257 undergraduate participants from the Chinese Undergraduates Cohort to undergo measurements of blood nickel levels and lung function. The follow-up study was conducted in May 2021. A linear mixed-effects model was employed to assess the relationship between blood nickel levels and lung function. We also conducted stratified analyses by home address. In addition, in order to explore the biological mechanism of lung function damage caused by nickel exposure, we performed metabolomic analyses of baseline serum samples (N = 251). Both analysis of variance and mixed linear effect models were utilized to assess the impact of blood nickel exposure on metabolism. Our findings from cross-sectional and cohort analyses revealed a significant association between blood nickel levels and decreased forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC) among young adults in the general population. Furthermore, we found stronger associations in urban areas. In metabolomics analysis, a total of nine metabolites were significantly changed under blood nickel exposure. The changed metabolites were mainly enriched in six pathways including carbohydrate, amino acid, and cofactor vitamin metabolism. These metabolic pathways involve inflammation and oxidative stress, indicating that high concentrations of nickel exposure can cause inflammation and oxidative stress by disrupting the above metabolism of the body.

Elemental impurities (heavy metals) in kratom products: an assessment of published individual product analyses.

INTRODUCTION: Kratom is commonly used by consumers, and the elemental impurity exposure that consumers would have at different kratom ingestion doses has been determined. METHODS: This assessment used original data from independent third-party laboratory testing of kratom products to identify the percentage of products that exceeded permissible daily exposure limits for lead (5 µg/day), nickel (200 µg/day), arsenic (15 µg/day), and cadmium (5 µg/day), the interim reference level for lead in adults (12.5 µg/day), and the tolerable upper intake level for manganese (11 mg/day) and nickel (1 mg/day). We assessed all products regardless of type and then evaluated non-extract products, extract products, and a soda preparation separately for elemental impurities. RESULTS: Three assessments of elemental impurities in kratom products have been published, totaling 68 products. Assessing all products and assuming a 3 g daily dose of kratom, 7.4% would exceed the permissible daily exposure limits for lead, 0% for nickel, 3.1% for arsenic, and 0% for cadmium. At a kratom dose of 25 g daily, 70.6% would exceed the permissible daily exposure limits for lead, 20.6% for nickel, 9.4% for arsenic, and 0% for cadmium. The interim reference level for lead would be exceeded by 1.5% of products at a kratom daily dose of 3 g and 33.8% of products at 25 g. The tolerable upper intake level for manganese would be exceeded by 12.5% of products at a kratom daily dose of 3 g and 41.7% of products at 25 g. Non-extract products generally contain greater concentrations of elemental impurities than extract products or the soda preparation. DISCUSSION: Apart from their concentrations in a gram of product, assessing the amount of exposure to elemental impurities at different kratom ingestion doses is also important. Elemental impurities exceeding regulatory permissible concentrations for many products, especially with greater daily kratom ingestion doses, may impact human health. CONCLUSIONS: Some kratom products contain excessive concentrations of elemental impurities of toxicological concern, such as lead and arsenic. Non-extract products (powders, capsules, tablets) generally contain greater concentrations of elemental impurities than extract products or the soda preparation. Daily use of these products can result in exposures exceeding regulatory thresholds and adverse health effects.

Facile Combination of Bismuth Vanadate with Nickel Tellurium Oxide for Efficient Photoelectrochemical Catalysis of Water Oxidation Reactions.

Bismuth vanadate (BVO) having suitable band edges is one of the effective photocatalysts for water oxidation, which is the rate-determining step in the water splitting process. Incorporating cocatalysts can reduce activation energy, create hole sinks, and improve photocatalytic ability of BVO. In this work, the visible light active nickel tellurium oxide (NTO) is used as the cocatalyst on the BVO photoanode to improve photocatalytic properties. Different NTO amounts are deposited on the BVO to balance optical and electrical contributions. Higher visible light absorbance and effective charge cascades are developed in the NTO and BVO composite (NTO/BVO). The highest photocurrent density of 6.05 mA/cm2 at 1.23 V versus reversible hydrogen electrode (VRHE) and the largest applied bias photon-to-current efficiency (ABPE) of 2.13% are achieved for NTO/BVO, while BVO shows a photocurrent density of 4.19 mA/cm2 at 1.23 VRHE and ABPE of 1.54%. Excellent long-term stability under light illumination is obtained for NTO/BVO with photocurrent retention of 91.31% after 10,000 s. The photoelectrochemical catalytic mechanism of NTO/BVO is also proposed based on measured band structures and possible interactions between NTO and BVO. This work has depicted a novel cocatalytic BVO system with a new photocharging material and successfully achieves high photocurrent densities for catalyzing water oxidation.