Cr leaching is anticipated to extensively advance the activity of Cr-containing catalysts towards the oxygen evolution reaction(OER),but the underlying catalytic enhancement mechanism requires further investigation.He...Cr leaching is anticipated to extensively advance the activity of Cr-containing catalysts towards the oxygen evolution reaction(OER),but the underlying catalytic enhancement mechanism requires further investigation.Herein,NiFeCr layered double hydroxide(NiFeCr-LDH)is proposed as a proof-of-concept catalyst to elucidate the evolution of Cr species and its enhancement mechanism in OER.The incorporation of Cr(Ⅲ)ions into the lattice of NiFe-LDH is achieved through a meticulously controlled electrodeposition process,which not only promotes Cr leaching but also deepens surface reconstruction.More importantly,experimental and theoretical results demonstrate that protogenetic CrO_(4)^(2-)anions,derived from the oxidation of leached Cr ions,adsorb onto the surface NiFeCr-LDH under the anodic potential to create a CrO_(4)^(2-)-rich electrical double layer(CrO_(4)^(2-)-rich EDL)and function as co-catalyst to trigger OER.CrO_(4)^(2-)-rich EDL integrated with vacancies balances the Gibbs free energies of the reconstructed NiFeCr-LDH for oxygen-containing intermediates,resulting in an exceptionally low overpotential of 286 mV at 500 mA cm^(−2),which outperforms most state-of-the-art metallic catalysts.Additionally,the anion exchange membrane water electrolysis system assembled with NiFeCr-LDH and Pt/C demonstrates 1000-h stability at a current density of 1.0 A cm^(−2)under a voltage of 1.74 V(at 70°C),highlighting its promising potential for practical,large-scale and sustainable applications.展开更多
Considerable levels of methylmercury(MeHg)have been found rice-based infant cereals as a result of MeHg transfer from the rice as a raw material to the products,hence consumption of rice products may pose a potential ...Considerable levels of methylmercury(MeHg)have been found rice-based infant cereals as a result of MeHg transfer from the rice as a raw material to the products,hence consumption of rice products may pose a potential health risk to infants who may receive cereals as the major diets and are susceptible to toxicity of MeHg.Determination of bioaccessibility of MeHg would provide a more accurate assessment of MeHg exposure through consumption of rice-based cereals,yet this information remains lacking.Further,the re-adsorption of methylmercury on the residual food will affect the accurate assessment of its bioaccessibility.Our goals in this work were 1)to determine the bioaccessibility of MeHg in infant rice cereals commonly available on the market by using a typical in vitro artificial gastrointestinal digestionmodel and 2)to evaluate the effects of MeHg re-adsorption on the in vitro assessment of MeHg bioaccessibility.The determined bioaccessibility of MeHg in the studied rice cereals after the standard dual-step(using gastric followed by intestinal juice)protocol ranged from 25%to 74%,a wide range comparable to that of fish samples observed here and in previous studies.The surprisingly higher bioaccessibility of MeHg in fish and rice cereals after the gastric step only,in comparison to after the complete two-step gastrointestinal digestion,suggests the re-adsorption of MeHg on the residual food.Separate experiments with spiked MeHg standards confirmed that the MeHg released by the acetic gastric juice was re-adsorbed on the residues during the intestinal step at neutral pH.This study provided first-hand data on the bioaccessibility of MeHg in infant rice cereals and methodological implications on using in vitro digestion to evaluate the bioaccessibility of MeHg and metal contaminants in general.展开更多
基金the support of this research by the National Key Research and Development Program of China(2024YFB4106400)the National Natural Science Foundation of China(22179035)the Science Fund for Distinguished Young Scholars of Heilongjiang Province(JQ2022B001)。
文摘Cr leaching is anticipated to extensively advance the activity of Cr-containing catalysts towards the oxygen evolution reaction(OER),but the underlying catalytic enhancement mechanism requires further investigation.Herein,NiFeCr layered double hydroxide(NiFeCr-LDH)is proposed as a proof-of-concept catalyst to elucidate the evolution of Cr species and its enhancement mechanism in OER.The incorporation of Cr(Ⅲ)ions into the lattice of NiFe-LDH is achieved through a meticulously controlled electrodeposition process,which not only promotes Cr leaching but also deepens surface reconstruction.More importantly,experimental and theoretical results demonstrate that protogenetic CrO_(4)^(2-)anions,derived from the oxidation of leached Cr ions,adsorb onto the surface NiFeCr-LDH under the anodic potential to create a CrO_(4)^(2-)-rich electrical double layer(CrO_(4)^(2-)-rich EDL)and function as co-catalyst to trigger OER.CrO_(4)^(2-)-rich EDL integrated with vacancies balances the Gibbs free energies of the reconstructed NiFeCr-LDH for oxygen-containing intermediates,resulting in an exceptionally low overpotential of 286 mV at 500 mA cm^(−2),which outperforms most state-of-the-art metallic catalysts.Additionally,the anion exchange membrane water electrolysis system assembled with NiFeCr-LDH and Pt/C demonstrates 1000-h stability at a current density of 1.0 A cm^(−2)under a voltage of 1.74 V(at 70°C),highlighting its promising potential for practical,large-scale and sustainable applications.
基金supported by the National Natural Science Foundation of China(No.22306111)Shandong Provincial Natural Science Foundation of China(Nos.ZR2022QB242 and ZR2020ZD20).
文摘Considerable levels of methylmercury(MeHg)have been found rice-based infant cereals as a result of MeHg transfer from the rice as a raw material to the products,hence consumption of rice products may pose a potential health risk to infants who may receive cereals as the major diets and are susceptible to toxicity of MeHg.Determination of bioaccessibility of MeHg would provide a more accurate assessment of MeHg exposure through consumption of rice-based cereals,yet this information remains lacking.Further,the re-adsorption of methylmercury on the residual food will affect the accurate assessment of its bioaccessibility.Our goals in this work were 1)to determine the bioaccessibility of MeHg in infant rice cereals commonly available on the market by using a typical in vitro artificial gastrointestinal digestionmodel and 2)to evaluate the effects of MeHg re-adsorption on the in vitro assessment of MeHg bioaccessibility.The determined bioaccessibility of MeHg in the studied rice cereals after the standard dual-step(using gastric followed by intestinal juice)protocol ranged from 25%to 74%,a wide range comparable to that of fish samples observed here and in previous studies.The surprisingly higher bioaccessibility of MeHg in fish and rice cereals after the gastric step only,in comparison to after the complete two-step gastrointestinal digestion,suggests the re-adsorption of MeHg on the residual food.Separate experiments with spiked MeHg standards confirmed that the MeHg released by the acetic gastric juice was re-adsorbed on the residues during the intestinal step at neutral pH.This study provided first-hand data on the bioaccessibility of MeHg in infant rice cereals and methodological implications on using in vitro digestion to evaluate the bioaccessibility of MeHg and metal contaminants in general.
