Preparation of Waste Coffee-grounds Carbon and Study on Phenol Adsorption Ability

The waste coffee-grounds carbon(WCGC)was prepared with H_(3)PO_(4)treated using waste coffee-grounds as precursor.Its adsorption ability was studied using phenol as test molecule.The influence of H_(3)PO_(4)treated,calcined temperature,the initial phenol concentration,the doge of carbon and original pH values on phenol adsorption ability were investigated.Characterization of WCGC was performed by N_(2)adsorption isotherms,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),and X-ray diffraction(XRD)techniques.First,the second order and Weber-Morris model reaction rate models were used to estimate the WCGC adsorption ability.The results show that the produced WCGC(700℃,2 h)has been graphitized and the layered structure increased BET surface to 435.98 m^(2)/g and adsorption phenol ability.The initial phenol concentration is 50 mg/L,the amount of WCGC(700℃,2 h)is 0.2 g,and the phenol adsorption rate is 97%after 270 min and no intermediate product formation.The adsorption kinetics of the selected WCGC is best fitted by the Weber-Morris model.

Adsorption ability of rare earth elements on clay minerals and its practical performance

The adsorption behaviors of rare earth elements on clay minerals would have great influence on the mineralization process and the leaching process of the ion-adsorption type rare earths ore.In this work,the adsorption thermodynamics of REEs on kaolin were investigated thoroughly and systematically.The experimental results showed that the adsorption characteristics of La,Nd,Y on kaolin did fit well with the Langmuir isotherm model and their saturated adsorption capacities were 1.731,1.587 and 0.971 mg/g,respectively.The free energy change（ΔG）values were –16.91 kJ/mol（La）,–16.05 kJ/mol（Nd）and –15.58 kJ/mol（Y）,respectively.The negative values of ΔG demonstrated that the adsorption of rare earth on kaolin was a spontaneously physisorption process.The deposit characteristic of the volcanic ion-adsorption type rare earths ore and the behavior of the rare earth in the column leaching process were also developed here.With the increase of the ore body depth,the distribution of the LREEs decreased and the HREEs increased.And the slight differences in the adsorption ability of REEs on clay minerals led to the fractionation effect in the column leaching process.These developed more evidences and better understanding of metallogenic regularity,and provided a theoretical basis and scientific approach to separation of the HREEs and LREEs in the leaching process.

Unexpected Adsorption Capacity of Ca-deficient Hydroxyapatite in Oil/water System

Herein, for the first time, we report the unexpected and interesting adsorption capacity of hydroxyapatites to a variety of organics in the presence of water, whose sorption amount could be up to 6 g·g^-1.

In situ decoration of CoP/Ti_(3)C_(2)Tx composite as efficient electrocatalyst for Li-oxygen battery

Application of Li-oxygen(Li-O_(2)) battery is in urgent need of bifunctional ORR/OER electrocatalyst. A surface-functionalization CoP/Ti_(3)C_(2)Txcomposite was fabricated theoretically, with the optimized electronic structure and more active electron, which is beneficial to the electrochemical reaction. The accordion shaped Ti_(3)C_(2)Txis featured with large specific surface area and outstanding electronic conductivity, which is beneficial for the adequate exposure of active sites and the deposition of Li2O2. Transition metal phosphides provide more electrocatalytic active sites and present good electrocatalytic effect. The CoP/Ti_(3)C_(2)Txcomposite served as the electrocatalyst of Li-O_(2)battery reaches a high specific discharge capacity of 17,413 m Ah/g at 100 m A/g and the lower overpotential of 1.25 V, superior to those of the CoP and Ti_(3)C_(2)Txindividually. The composite of transition metal phosphides and MXene are applied in Li-O_(2)battery, not only demonstrating higher cycling stability of the prepared CoP/Ti_(3)C_(2)Txcomposite, but pointing out the direction for their electrochemical performance improvement.

High-valance molybdenum doped Co_(3)O_(4) nanowires:Origin of the superior activity for 5-hydroxymethyl-furfural oxidation

Co_(3)O_(4) has been widely explored in electrocatalytic 5-hydroxymethyl-furfural(HMF) oxidation. However,the poor intrinsic ability has seriously limited its electrochemical ability. Heteroatom-doping is an efficient method to enhance the electrocatalytic ability of catalyst by regulating electronic structure. Herein,we have modulated the electronic structure of Co_(3)O_(4) by high valance Mo^(6+)-doping. With the introduction of Mo^(6+), the content of Co^(2+) was increased and metal-oxygen bond was strength. Electrochemical results suggested that the electrocatalytic ability of Co_(3)O_(4) towards HMF oxidation has been dramatically improved and reaction kinetics has been fasten. Theoretical calculations demonstrated that the surrounding cobalt sites after Mo^(6+)-doping with assembled electron has a strong adsorption ability towards HMF molecule leading to more favourable oxidation of HMF. Post characterizations demonstrated pristine Co_(3)O_(4) structure was kept after electrolysis cycles and CoOOH active species were formed. This work provides a valuable reference for developing efficient heteroatom-doped electrocatalysts for HMF oxidation.

Revealing the importance of suppressing formation of lithium hydride and hydrogen in Li anode protection

The reviving of the“Holy Grail”lithium metal batteries(LMBs)is greatly hindered by severe parasitic reactions between Li anode and electrolytes.Herein,first,we comprehensively summarize the failure mechanisms and protection principles of the Li anode.Wherein,despite being in dispute,the formation of lithium hydride(LiH)is demonstrated to be one of the most critical factors for Li anode pulverization.Secondly,we trace the research history of LiH at electrodes of lithium batteries.In LMBs,LiH formation is suggested to be greatly associated with the generation of H_(2)from Li/electrolyte intrinsic parasitic reactions,and these intrinsic reactions are still not fully understood.Finally,density functional theory calculations reveal that H_(2)adsorption ability of representative Li anode protective species(such as LiF,Li_(3)N,BN,Li_(2)O,and graphene)is much higher than that of Li and LiH.Therefore,as an important supplement of well-known lithiophilicity theory/high interfacial energy theory and three key principles(mechanical stability,uniform ion transport,and chemical passivation),we propose that constructing an artificial solid electrolyte interphase layer enriched of components with much higher H_(2)adsorption ability than Li will serve as an effective principle for Li anode protection.In summary,suppressing formation of LiH and H_(2)will be very important for cycle life enhancement of practical LMBs.

Titanate Nanorods Modified with Nanocrystalline ZnS Particles and Their Photocatalytic Activity on Pollutant Removal

Aiming to produce materials with enhanced photocatalytic properties, the synthesis of new crystalline nanocomposites by combining titanate nanorods（TNR） with ZnS nanocrystallites is described in this work.The TNR modification was accomplished by an in situ nucleation and growth process of ZnS nanoparticles.Zinc diethyldithiocarbamate was used as the metal chalcogenide precursor. The prepared materials were structural, morphological and optical characterized by X-ray diffraction, transmission electron microscopy and high resolution transmission electron microscopy, energy dispersive spectroscopy and powder diffuse reflectance spectra. Crystalline Zn S nanoparticles were obtained as a homogeneous and continuous layer, covering completely the TNR surface. The application of these new nanocomposite materials on photocatalytic degradation of pollutants was investigated. First, the evaluation of hydroxyl radical formation, using the terephthalic acid as probe, was studied. Afterwards, the adsorption and photodegradation of safranine-T, used here as a model pollutant molecule, was investigated. The obtained data indicate that the prepared nanocomposites have potential to be used as photocatalysts for organic pollutant removal.The best removal results（97% removal） were obtained using the 0.01 Zn S/HTNR sample as catalyst（0.2 g/L; 10 ppm safranin-T solution） with a combination of a low dye adsorption（20%） and a high dye photocatalytic degradation（77%）.

Pseudo-copper Ni–Zn alloy catalysts for carbon dioxide reduction to C_(2) products

Electrocatalytic CO_(2) reduction reaction(CO_(2)RR)to obtain C_(2) products has drawn widespread attentions.Copper-based materials are the most reported catalysts for CO_(2) reduction to C_(2) products.Design of high-efficiency pseudo-copper catalysts according to the key characteristics of copper(Cu)is an important strategy to understand the reaction mechanism of C_(2) products.In this work,density function theory(DFT)calculations are used to predict nickel–zinc(NiZn)alloy catalysts with the criteria similar structure and intermediate adsorption property to Cu catalyst.The calculated tops of 3d states of NiZn3(001)catalysts are the same as Cu(100),which is the key parameter affecting the adsorption of intermediate products.As a result,NiZn3(001)exhibits similar adsorption properties with Cu(100)on the crucial intermediates*CO_(2),*CO and*H.Moreover,we further studied CO formation,CO hydrogenation and C–C coupling process on Ni–Zn alloys.The free energy profile of C_(2) products formation shows that the energy barrier of C_(2) products formation on NiZn3(001)is even lower than Cu(100).These results indicate that NiZn3 alloy as pseudo-copper catalyst can exhibit a higher catalytic activity and selectivity of C_(2) products during CO_(2)RR.This work proposes a feasible pseudo-copper catalyst and provides guidance to design high-efficiency catalysts for CO_(2)RR to C_(2) or multi-carbon products.