The highly selective catalytic hydrogenation of halogenated nitroaromatics was achieved by employing Pd‑based catalysts that were co‑modified with organic and inorganic ligands.It was demonstrated that the catalysts contained Pd species in mixed valence states,with high valence Pd at the metal‑support interface and zero valence Pd at the metal surface.While the strong coordination of triphenylphosphine(PPh3)to Pd0 on the Pd surface prevents the adsorption of halogenated nitroaromatics and thus dehalogenation,the coordination of sodium metavanadate(NaVO3)to high‑valence Pd sites at the interface helps to activate H2 in a heterolytic pathway for the selective hydrogenation of nitro‑groups.The excellent catalytic performance of the interfacial active sites enables the selective hydrogenation of a wide range of halogenated nitroaromatics.
Efficient selective adsorption and separation using porous frameworks are critical in many industrial processes,where adsorption energy and dynamic diffusion rate are predominant factors governing selectivity.They are highly susceptible to framework charge,which plays a significant role in selective adsorption.Currently,ionic porous frameworks can be divided into two types.One of them is composed of a charged backbone and counter ions.The framework with zwitterionic channels is another type.It is composed of regular and alternating arrangements of cationic and anionic building units.Herein,we report a hydrogen-bonded ionic framework(HIF)of{(CN_(3)H_(6))_(2)[Ti(μ_(2)-O)(SO_(4))_(2)]}_nwith 1D channel exhibits unique adsorption selectivity for Ar against N_(2)and CO_(2).Density functional theory(DFT)results suggest that CO_(2)cannot be adsorbed by HIF at the experimental temperature due to a positive adsorption free energy.In addition,due to a relatively large diffusion barrier at 77 K,N_(2)molecules hardly diffuse in HIF channels,while Ar has a negligible diffusion barrier.The unique net positively-charged space in the channel is the key to the unusual phenomena,based on DFT simulations and structural analysis.The findings in this work proposes the new adsorption mechanism and provides unique perspective for special separation applications,such as isotope and noble gasses separations.
Electrocatalytic reduction of nitrate to ammonia has been considered a promising and sustainable pathway for pollutant treatment and ammonia has significant potential as a clean energy.Therefore,the method has received much attention.In this work,Cu/Fe 2D bimetallic metal-organic frameworks were synthesized by a facile method applied as cathode materials without high-temperature carbonization.Bimetallic centers(Cu,Fe)with enhanced intrinsic activity demonstrated higher removal efficiency.Meanwhile,the 2D nanosheet reduced themass transfer barrier between the catalyst and nitrate and increased the reaction kinetics.Therefore,the catalysts with a 2D structure showed much better removal efficiency than other structures(3D MOFs and BulkMOFs).Under optimal conditions,Cu/Fe-2D MOF exhibited high nitrate removal efficiency(87.8%)and ammonium selectivity(89.3%)simultaneously.The ammonium yielded up to significantly 907.2μg/(hr·mg_(cat))(7793.8μg/(hr·mg_(metal)))with Faradaic efficiency of 62.8%at an initial 100 mg N/L.The catalyst was proved to have good stability and was recycled 15 times with excellent effect.DFT simulations confirm the reduced Gibbs free energy of Cu/Fe-2D MOF.This study demonstrates the promising application of Cu/Fe-2D MOF in nitrate reduction to ammonia and provides new insights for the design of efficient electrode materials.
Qian MaYinghao XueChuning ZhangYanyan ChenWei TengHua ZhangJianwei Fan
Chloroform and other volatile organic pollutants have garnered widespread attention from the public and researchers,because of their potential harm to the respiratory system,nervous system,skin,and eyes.However,research on chloroform vapor sensing is still in its early stages,primarily due to the lack of specific recognition motif.Here we report a mesoporous photonic crystal sensor incorporating carbon dots-based nanoreceptor(HMSS@CDs-PCs)for enhanced chloroform sensing.The colloidal PC packed with hollow mesoporous silica spheres provides an interconnected ordered macro-meso-hierarchical porous structure,ideal for rapid gas sensing utilizing the photonic bandgap shift as the readout signal.The as-synthesized CDs with pyridinic-N-oxide functional groups adsorbed in the hollow mesoporous silica spheres are found to not only serve as the chloroform adsorption sites,but also a molecular glue that prevents crack formation in the colloidal PC.The sensitivity of HMSS@CDs-PCs sensor is 0.79 nm ppm^(-1)and an impressively low limit of detection is 3.22 ppm,which are the best reported values in fast-response chloroform vapor sensor without multi-signal assistance.The positive response time is 7.5 s and the negative response time 9 s.Furthermore,relatively stable sensing can be maintained within a relative humidity of 20%-85%RH and temperature of 25-55℃.This study demonstrates that HMSS@CDs-PCs sensors have practical application potential in indoor and outdoor chloroform vapor detection.
Respiratory rate monitoring is of great significance in pig healthy breeding for the early detection and timely prevention of respiratory diseases.Humidity sensing is an important noncontact method to monitor pig respiration,which does not cause direct harm to pigs and meets the requirements of animal welfare.This paper proposes a humidity sensor based on graphene oxide wrapped-silica microspheres(GO@SiO_(2)).First,the sensor shows fast response/recovery performances of 0.24/0.73 s.Experiments demonstrate that the wrapped microsphere structure can inhibit water aggregation.It is speculated that the wrapped microsphere structure can inhibit the stacking of GO,and its curved surface can promote the evaporation of water molecules.Second,the sensor shows a high sensitivity of 1.2%/%RH-4.2%/%RH in 11%-95%RH range.This can be attributed to different sensing mechanisms,from hopping transport to increasing ion transport,leading to a significant change in the sensor’s resistance.Third,the sensor shows selectivity to water molecules due to the hydrophilic characteristic of GO and the significant increase in conductivity by ion transport.Finally,the sensor is applied to realize the respiratory rate monitoring of adult pigs and piglets.
Jing LIBo LIZiqi LIAOYunhui DUANXinglan FUYuehua HUANGGuanglin LI
Methanol synthesis via CO_(2) hydrogenation stands as a pivotal avenue for CO_(2) conversion and fixation,garnering extensive investigation.Diverse reactor configurations and energy supplies,alongside a spectrum of catalyst formulations,have been developed to enhance reaction metrics including conversion,selectivity,productivity,and stability.Integrating state-of-the-art Cu-based catalysts from thermal catalysis into a photothermal reactor yielded notable results,achieving an overall CO_(2) conversion of 98%and methanol selectivity of 86%.Utilizing the liquid out/gas in concept(LOGIC)reactor,in which only the catalyst bed is irradiated to raise its temperature,facilitated the condensation of products(H_(2)O and CH3OH),due to their low vapor pressure.The lower concentration of products in vapor phases ensured the continuous progress of the reaction.The synergistic integration of reactor design and catalyst fabrication could capitalize on the strengths of both components and lead to enhanced performance in methanol synthesis.
Lingzhen ZengYongfang SunTingting WangZeyan CenMaolin WangOriol AngurellMeng WangDing Ma
