Nickel-iron layered double hydroxide （NiFe-LDH） nanosheets have shown optimal oxygen evolution reaction （OER） performance; however, the role of the intercalated ions in the OER activity remains unclear. In this wo...Nickel-iron layered double hydroxide （NiFe-LDH） nanosheets have shown optimal oxygen evolution reaction （OER） performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential （high reducing ability）, such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential （low reducing ability）, such as fluorion, show a high overpotential of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. This increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.展开更多
Sustainable light energy from ambient environment has attracted particular attention to meet the evergrowing need of small-scale electronics.The modulation of intercorrelated thermal and electronic transport is one of...Sustainable light energy from ambient environment has attracted particular attention to meet the evergrowing need of small-scale electronics.The modulation of intercorrelated thermal and electronic transport is one of the crucial aspects for reliable photothermoelectric electronics.Herein,a defectpromoted photothermoelectric effect is demonstrated in densely aligned ZnO nanorod array with rich lattice defects.The defect-rich ZnO device delivers high electrical conductivity and large Seebeck coefficient to enable significant improvement of photothermoelectric energy conversion and self-powered photodetection.The position sensitivity reaches approximately 0.19 mV mm^(-1),and the temperature gradient induced electric field makes up for the suppression in the photothermoelectric process.The synergism between intrinsic defects and extra temperature field plays an important role in promoting the photothermoelectric properties of dense ZnO nanorod array.This study is interesting for interpreting the thermo-phototronic phenomena as well as demonstrating the possibility of defect engineering and phonon engineering to enable highly efficient light energy scavenging and self-powered photodetection.展开更多
基金supported by Taishan Scholar Program of Shandong Province(tsqn201812055,tspd20181208)the National Natural Science Foundation of China(51973099)+2 种基金the Central Government Guiding Funds for Local Science and Technology Development(Z135050009017,2022ZY015)the Open Laboratory of State Key Laboratory of Organic and Inorganic Composites(oic-202301006)the Youth Innovation Team Project of Shandong Province,China(2021KJ018)。
基金This work was supported by the National Natural Science Foundation of China （NSFC）, the National Key Research and Development Project （Nos. 2016YFF0204402 and 2016YFC0801302）, the Program for Changjiang Scholars, and innovative Research Team in the University, and the Fundamental Research Funds for the Central Universities, and the long term subsidy mechanism from the Ministry of Finance and the Ministry of Education of China. S. S. gratefully acknowledges Villum Foundation.
文摘Nickel-iron layered double hydroxide （NiFe-LDH） nanosheets have shown optimal oxygen evolution reaction （OER） performance; however, the role of the intercalated ions in the OER activity remains unclear. In this work, we show that the activity of the NiFe-LDHs can be tailored by the intercalated anions with different redox potentials. The intercalation of anions with low redox potential （high reducing ability）, such as hypophosphites, leads to NiFe-LDHs with low OER overpotential of 240 mV and a small Tafel slope of 36.9 mV/dec, whereas NiFe-LDHs intercalated with anions of high redox potential （low reducing ability）, such as fluorion, show a high overpotential of 370 mV and a Tafel slope of 80.8 mV/dec. The OER activity shows a surprising linear correlation with the standard redox potential. Density functional theory calculations and X-ray photoelectron spectroscopy analysis indicate that the intercalated anions alter the electronic structure of metal atoms which exposed at the surface. Anions with low standard redox potential and strong reducing ability transfer more electrons to the hydroxide layers. This increases the electron density of the surface metal sites and stabilizes their high-valence states, whose formation is known as the critical step prior to the OER process.
基金This work was supported by the National Natural Science Foundation of China(Nos.51973099,21761029)Taishan Scholar Program of Shandong Province(No.tsqn201812055)+3 种基金First Division Alar Science and Technology Plan Project in Xinjiang Corps(2019GJJ04)the State Key Laboratory of Bio-Fibers and Eco-Textiles(Qingdao University)(Nos.ZKT04,GZRC202007)the Dean Project of Guangxi Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology(No.2017K005)Training Program for Outstanding Young Teachers in Xinjiang Corps,and the Engineering Laboratory of Chemical Resources Utilization in South Xinjiang of Xinjiang Production and Construction Corps(CRUZD2003).
文摘Sustainable light energy from ambient environment has attracted particular attention to meet the evergrowing need of small-scale electronics.The modulation of intercorrelated thermal and electronic transport is one of the crucial aspects for reliable photothermoelectric electronics.Herein,a defectpromoted photothermoelectric effect is demonstrated in densely aligned ZnO nanorod array with rich lattice defects.The defect-rich ZnO device delivers high electrical conductivity and large Seebeck coefficient to enable significant improvement of photothermoelectric energy conversion and self-powered photodetection.The position sensitivity reaches approximately 0.19 mV mm^(-1),and the temperature gradient induced electric field makes up for the suppression in the photothermoelectric process.The synergism between intrinsic defects and extra temperature field plays an important role in promoting the photothermoelectric properties of dense ZnO nanorod array.This study is interesting for interpreting the thermo-phototronic phenomena as well as demonstrating the possibility of defect engineering and phonon engineering to enable highly efficient light energy scavenging and self-powered photodetection.
