Thermodynamically controllable synthesis of ZIF-8 exposing different facets and their applications in single atom catalytic oxygen reduction reactions

The development of thermodynamically controllable synthetic strategy to manipulate the morphology of ZIF-8 without capping agent is essential to help understanding their facet effect and the structure-activity relationship of single atom catalysts derived from ZIF-8.Here,we prepared ZIF-8 with different morphologies(cube,truncated rhombododecahedral and rhombododecahedral)and thus area ratio of exposed{100},{110}facets by a thermodynamically controllable synthetic strategy.When the reaction proceeds under room temperature(30℃),the assembling of ZIF-8 followed an area-reducing layered growth mode,while switched to an integral layered growth mode at lower temperature-40℃.Moreover,this strategy also works to obtain ZIF-8 encapsulated with metal precursors(Fe(acac)_(3),Cu(acac)_(2)and Co(acac)_(2)).Single Fe atom anchored on nitrogen doped carbon catalysts(SA-Fe/CN)derived from Fe-ZIF-8 retain their original morphologies and the unsaturated surface-active sites on{100}facet,which further displays different catalytic performance towards oxygen reduction reaction(ORR).This work not only reveals the different growth pattern of ZIF-8,but also points out a new direction for designing and synthesizing MOFs with different morphology rationally.

Atomically dispersed Ni anchored on polymer-derived mesh-like Ndoped carbon nanofibers as an efficient CO_(2) electrocatalytic reduction catalyst

Efficient electroreduction of CO_(2) into CO and other chemicals turns greenhouse gases into fuels and value-added chemicals,holding great promise for a closed carbon cycle and the alleviation of climate changes.However,there are still challenges in the large-scale application of CO_(2) electroreduction due to the sluggish kinetics.Herein we develop a self-assembly strategy to synthesize a highly efficient CO_(2) reduction electrocatalyst with atomically dispersed Ni-N_(4) active centers anchored on polymerderived mesh-like N-doped carbon nanofibers(Ni-N_(4)/NC).The Ni-N_(4)/NC exhibits high selectivity for CO_(2) reduction reaction with CO Faradaic efficiency(CO FE)above 90% over a wide potential range from−0.6 to−1.0 V vs.RHE.The catalyst reaches a maximum CO FE up to 98.4% at−0.8 V with a TOF of 1.28×10^(5) h^(–1) and Tafel slope of 113 mV·dec^(–1).The catalyst also exhibits remarkable stability,with little change in current density and CO FE over a 10-hour durability test at–0.8 V vs.RHE.This method provides a new route for the synthesis of highly efficient CO_(2) reduction electrocatalyst.

Porous γ-Fe_(2)O_(3) nanoparticle decorated with atomically dispersed platinum: Study on atomic site structural change and gas sensor activity evolution

Decorating semi-conducting metal oxide with noble metal has been recognized as a viable approach to improve the sensitivity of gas sensor. However, conventional method which relys on noble metal nanoparticles is confronted with drawback of significantly increased cost. To maximize the atom efficiency and reduce the cost for practical industrial application, designing sensor material with noble metal isolated single atom sites (ISAS) doping is a desired option. Here, we report an atomically dispersed platinum on one-dimensional arranged porous γ-Fe2O3 nanoparticle composites as highly efficient ethanol gas sensor. The optimized sample (Pt1-Fe2O3-ox) exhibited a high response (Ra/Rg = 102.4) and good selectivity to ethanol gas. It is demonstrated only the Pt single atom sites with high valance can effectively promote the adsorption capacity to ethanol and consequently enhance the sensitivity of sensing process by changing the electrical structure of Fe2O3 support. This work indicates the single atom sites could play a vital role in improving the performance of conventional metal oxides gas sensors and pave way for the exploration of ISAS-enhanced gas sensor for other volatile organic compounds (VOCs).

Genome-wide CRISPR activation screen identifies candidate receptors for SARS-CoV-2 entry

The outbreak of coronavirus disease 2019(COVID-19) caused by SARS-CoV-2 has created a global health crisis. SARS-CoV-2 infects varieties of tissues where the known receptor ACE2 is low or almost absent, suggesting the existence of alternative viral entry pathways. Here, we performed a genome-wide barcoded-CRISPRa screen to identify novel host factors that enable SARS-CoV-2 infection. Beyond known host proteins, i.e., ACE2, TMPRSS2, and NRP1, we identified multiple host components,among which LDLRAD3, TMEM30A, and CLEC4G were confirmed as functional receptors for SARS-CoV-2. All these membrane proteins bind directly to spike’s N-terminal domain(NTD). Their essential and physiological roles have been confirmed in either neuron or liver cells. In particular, LDLRAD3 and CLEC4G mediate SARS-CoV-2 entry and infection in an ACE2-independent fashion. The identification of the novel receptors and entry mechanisms could advance our understanding of the multiorgan tropism of SARS-CoV-2, and may shed light on the development of COVID-19 countermeasures.