Design strategies for rechargeable aqueous metal-ion batteries

Rechargeable aqueous metal-ion batteries(AMBs)have attracted extensive scientific and commercial interest due to their potential for cost-effective,highly safe,and scalable stationary energy storage.However,their limited output voltage,inadequate energy density,and poor reversibility of ambiguous electrode reactions in aqueous electrolytes strongly limit their practical viability.This review aims to elucidate the challenges of existing AMBs from the material design to whole device applications.We summarize the emerging electrochemistry,fundamental properties,and key issues in interfacial behaviors of various classes of prevailing AMBs,including aqueous alkali metal-ion batteries and multivalent-ion batteries,and present an appraisal of recent advances for addressing the performance deficiency.Specifically,the progress of zinc-ion batteries is highlighted to provide a ubiquitous guideline for their commercialization in the grid-scale energy storage.Finally,we figure out the dominating general challenges for achieving high-performance AMBs,laying out a perspective for future breakthroughs.

Progress on metal-support interactions in Pd-based catalysts for automobile emission control

The interactions between metals and oxide supports,so-called metal-support interactions(MSI),are of great importance in heterogeneous catalysis.Pd-based automotive exhaust control catalysts,especially Pd-based three-way catalysts (TWCs),have received considerable research attention owing to its prominent oxidation activity of HCs/CO,as well as excellent thermal stability.For Pd-based TWCs,the dispersion,chemical state and thermal stability of Pd species,which are crucial to the catalytic performance,are closely associated with interactions between metal nanoparticles and their supporting matrix.Progress on the research about MSI and utilization of MSI in advanced Pd-based three-way catalysts are reviewed here.Along with the development of advanced synthesis approaches and engine control technology,the study on MSI would play a notable role in further development of catalysts for automobile exhaust control.

Chemical deactivation of V2Os-WO3/Ti02 SCR catalyst by combined effect of potassium and chloride

V2O5-WO3/WiO2 catalyst was poisoned by impregnation with NHaC1, KOH and KC1 solution, respectively. The catalysts were characterized by X-ray diffraction （XRD）, inductively coupled plasma （ICP）, N2 physisorption, Raman, UV-vis, NH3 adsorption, temperature-programmed reduction of hydrogen （H2- TPR）, temperature-programmed oxidation of ammonia （NH3-TPO） and selective catalytic reduction of NOx with ammonia （NH3-SCR）. The deactivation effects of poison- ing agents follow the sequence of KC1 〉 KOH 〉〉 NH4CI. The addition of ammonia chloride enlarges the pore size of the titania support, and promotes the formation of highly dispersed V = O vanadyl which improves the oxidation of ammonia and the high-temperature SCR activity. K~ ions are suggested to interact with vanadium and tungsten species chemically, resulting in a poor redox property of catalyst. More importantly, potassium can reduce the Bronsted acidity of catalysts and decrease the stability of Bronsted acid sites significantly. The more severe deactivation of the KCl-treated catalyst can be mainly ascribed to the higher amount of potassium resided on catalyst.

Optimizing the crystallinity and acidity of H-SAPO-34 by fluoride for synthesizing Cu/SAPO-34 NH_3-SCR catalyst

A series of H-SAPO-34 zeolites were synthesized by a hydrothermal method in fluoride media.The as-synthesized H-SAPO-34 zeolites were characterized by X-ray diffraction（XRD）,scanning electron microscopy（SEM）,N_2 physisorption,temperature-programmed desorption of NH_3（NH_3-TPD） and nuclear magnetic resonance（NMR） measurements.The results showed that a certain concentration of F- anions promoted the nucleation and crystallization of H-SAPO-34.The H-SAPO-34 synthesized in the fluoride media showed high crystallinity,uniform particle size distribution,large specific surface area and pore volume,and enhanced acidity.Therefore,Cu/SAPO-34 based on the fluoride-assisted zeolite showed a broadened temperature window for the selective catalytic reduction of NO by NH_3（NH_3-SCR） reaction due to the enhanced acidity of the zeolite and the improved dispersion of copper species.

Deactivation of Cu-SAPO-34 by urea-related deposits at low temperatures and the regeneration

Selective catalytic reduction(SCR) with urea catalyzed by Cu-SAPO-34 is an effective method to eliminate NO_x from diesel exhaust. However, urea-related deposits may form during cold-start and urban driving due to low exhaust temperatures. The activity of CuSAPO-34 at 175°C is significantly degraded by urea exposure, and 300°C is required for regeneration. Through in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) and temperature-programmed hydrolysis studies, the dominant stable deposit at 175°C is identified as biuret, which can be eliminated at 300°C. The urea-derived deactivation and regeneration mechanisms of Cu-SAPO-34 were compared with those of anatase-supported catalysts.

Size effect of Pt nanoparticles in acid-assisted soot oxidation in the presence of NO

Pt/Al2O3 catalysts with mean Pt particle size ranged from 2.7 to 7.1 nm were synthesized by chemical reduction method,and the sulfated counterparts were prepared by impregnation of sulfuric acid.The turnover frequency of platinum for soot oxidation under loose contact conditions in a feed flow containing NO and O2 are positively correlated with the size of platinum.The sulfated Pt/Al2O3 exhibits higher catalytic activity for soot oxidation in the presence of NO despite their reduced ability for NO2 production.Such a contradiction is more significant for those catalysts with smaller platinum particles.Herein,the catalysts were characterized by X-ray diffraction(XRD),Brunauer-Emmett-Teller(BET),transmission electron microscopy(TEM),inductive coupled plasma(ICP)emission spectrometry,CO chemisorption,thermogravimetric analysis(TGA),NH3 temperature-programmed desorption(NH 3-TPD),NO temperature-programmed oxidation(TPO)and NO x temperatureprogrammed desorption(TPD).Possible effect of Pt particle size for the catalytic oxidation of soot in the presence of NO was presented based primarily on the promoted NO2 transfer efficiency onto the soot pushed by the acidic catalysts.

Effects of WOx modification on the activity, adsorption and redox properties of CeO_2 catalyst for NO_x reduction with ammonia

A series of WO3/CeO2 （WOx/CeO2） catalysts were synthesized by wet impregnation of ammonium metatungstate on a CeO2 support. The resulting solid acid catalysts were characterized by X-ray diffraction （XRD）, UV-Vis spectroscopy （UV-Vis）, Raman spectroscopy （Raman）, in-situ Fourier transform infrared spectroscopy （in-situ FT-IR） of ammonia adsorption, NH3-TPD, H2 temperature- programmed reduction （H2-TPR）, NH3/NO oxidation and activity measurements for NOx reduction by NH3 （NH3-SCR）. The results show that polytungstate （WOx） species are the main species of tungsten oxide on the surface of ceria. The addition of tungsten oxide enhances the BriSnsted acidity of ceria catalysts remarkably and decreases the amount of surface oxygen on celia, with strong interaction between CeO2 and WOx. As a result, the N2 selectivity of NH3 oxidation and NH3-SCR at high temperatures （〉 300℃） is enhanced. Therefore, a wide working temperature window in which NOx conversion exceeds 80% （NOx conversion 〉 80%） from 200 to 450℃, is achieved over 10 wt.% WOx/CeO2 catalyst. A tentative model of the NH3-SCR reaction route on WOx/CeO2 catalysts is presented.

Effect of water vapor on NH_3–NO/NO_2 SCR performance of fresh and aged MnO_x–NbO_x–CeO_2 catalysts

A MnOx-NbOx-CeO2 catalyst for low temperature selective catalytic reduction（SCR） of NOx with NH3 was prepared by a sol-gel method, and characterized by NH3-NO/NO2 SCR catalytic activity, NO/NH3 oxidation activity, NOx/NH3 TPD, XRD, BET, H2-TPR and in-situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy（DRIFTS）. The results indicate that the Mn Ox-Nb Ox-CeO2 catalyst shows excellent low temperature NH3-SCR activity in the temperature range of 150-300℃. Water vapor inhibits the low temperature activity of the catalyst in standard SCR due to the inhibition of NOx adsorption. As the NO2 content increases in the feed, water vapor does not affect the activity in NO2 SCR. Meanwhile, water vapor significantly enhances the N2 selectivity of the fresh and the aged catalysts due to its inhibition of the decomposition of NH4NO3 into N2O.

Comparative study of La(1-x)CexMnO(3+δ) perovskites and Mn-Ce mixed oxides for NO catalytic oxidation

A series of La1-xCexMnO3+δ(x=D,0.05,0.1,0.2,and 0.3)perovskites and Mn-Ce mixed oxides were prepared.Their physico-chemical properties were systematically characterized and the NO oxidation activities of the catalysts were investigated.The La0.9Ce0.1MnO3+δhas the best activity among all of the catalysts,with a maximum NO conversion of 85%at 300℃.The characterization results indicate that the doping of Ce improves the properties of the perovsidtes in terms of the specific surface area,the average valence state of Mn ions,the number of reactive oxygen species and the NOx desorption behaviors.The Mn-Ce mixed oxide calcined at 500℃shows a similar NO oxidation activity with La0.9Ce0.1MnO3+δ.However,the activity of the mixed oxide obtained at 750℃decreases a lot,which results from the loss of active sites and active oxygen species.

An isolation strategy to anchor atomic Ni or Co cocatalysts on TiO_(2)(A)for photocatalytic hydrogen production

TiO_(2) has been considered as an ideal photocatalyst for water splitting.However,narrow light absorbance,low charge separation efficiency,and rare surface active sites lead to the low photocatalytic efficiency of TiO_(2).Although extensive research attempted to improve the situation,there is still lack of method for constructing high active and noble-metal-free TiO_(2) photocatalyst for H_(2) evolution reactions(HER).In this work,we loaded single atomic(SA)Ni(or Co)on the surface of anatase TiO_(2)(TiO_(2)(A))nanosheets by an isolation strategy.Ethylene diamine tetraacetic acid and ethylene glycol(EDTA-EG)compounds were used to chelate metal ions in solution and form carbon quantum dots in the following thermal treatment to isolate the metal ions on surface of TiO_(2)(A).The prepared Ni SA/TiO_(2)(A)catalyst owned a“skin wrapped body”structure with in-situ formed twodimensional(2D)heterojunction facilitating the fast electron transfer.As a result,the Ni SA/TiO_(2)(A)catalyst showed a high H_(2) evolution rate of 2,900μmol·g−1·h−1.This work provides an isolation strategy for constructing promising single-atom metal catalyst for photocatalysis and beyond.

Carbon nanodots enhanced performance of Cs_(0.15)FA_(0.85)PbI_(3) perovskite solar cells

A high-quality hybrid Cs_(0.15)FA_(0.85)PbI_(3) thin film is deposited through doping of carbon nanodots(CNDs)into perovskite precursor solution.The corresponding inverted planar perovskite solar cells(PSCs)of ITO/PTAA/Cs_(0.15)FA_(0.85)PbI_(3)/PC_(61)BM/BCP/Ag exhibit an improvement in efficiency from 17.36%to 20.06%,which could be attributed to the passivation of the defects at the crystallized perovskite thin film and enhanced perovskite phase uniformity.The results of electron trap density indicate that the addition of CNDs significantly reduces the defects density at the perovskite thin film and the recombination of charge carriers in transport process is minimized.These results demonstrate that low-cost CNDs are effective additives for passivating defects,further reducing charge carrier recombination and improving device efficiency.