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The removal of acetylene impurities remains important yet challenging to the ethylene downstream industry. Current thermocatalytic semihydrogenation processes require high temperature and excess hydrogen to guarantee complete acetylene conversion. For this reason, renewable electricity-based electrocatalytic semihydrogenation of acetylene over Cu-based catalysts is an attractive route compared to the energy-intensive thermocatalytic processes. However, active Cu electrocatalysts still face competition from side reactions and often require high overpotentials. Here, we present an undercoordinated Cu nanodots catalyst with an onset potential of −0.15 V versus reversible hydrogen electrode that can exclusively convert C 2 H 2 to C 2 H 4 with a maximum Faradaic efficiency of ~95.9% and high intrinsic activity in excess of −450 mA cm −2 under pure C 2 H 2 flow. Subsequently, we successfully demonstrate simulated crude ethylene purification, continuously producing polymer-grade C 2 H 4 with <1 ppm C 2 H 2 for 130 h at a space velocity of 1.35 × 10 5  ml g cat −1 h −1 . Theoretical calculations and in situ spectroscopies reveal a lower energy barrier for acetylene semihydrogenation over undercoordinated Cu sites than nondefective Cu surface, resulting in the excellent C 2 H 2 -to-C 2 H 4 catalytic activity of Cu nanodots. Cu-based catalysts for the conversion of C 2 H 2 to C 2 H 4 are plagued by side reactions. Here, Cu nanodots for C 2 H 2 semihydrogenation are reported to reach current densities >400 mA cm −2 and selectively produce polymer-grade ethylene over 130 h.

Keywords: Coronavirus, COVID-19, Pandemics, Coronavirus infections, Remote consultation, Severe acute respiratory syndrome coronavirus 2

Heteroatom-doping is a practical means to boost RuO 2 for acidic oxygen evolution reaction (OER). However, a major drawback is conventional dopants have static electron redistribution. Here, we report that Re dopants in Re 0.06 Ru 0.94 O 2 undergo a dynamic electron accepting-donating that adaptively boosts activity and stability, which is different from conventional dopants with static dopant electron redistribution. We show Re dopants during OER, (1) accept electrons at the on-site potential to activate Ru site, and (2) donate electrons back at large overpotential and prevent Ru dissolution. We confirm via in situ characterizations and first-principle computation that the dynamic electron-interaction between Re and Ru facilitates the adsorbate evolution mechanism and lowers adsorption energies for oxygen intermediates to boost activity and stability of Re 0.06 Ru 0.94 O 2 . We demonstrate a high mass activity of 500 A g cata. −1 (7811 A g Re-Ru −1 ) and a high stability number of S-number = 4.0 × 10 6  n oxygen  n Ru −1 to outperform most electrocatalysts. We conclude that dynamic dopants can be used to boost activity and stability of active sites and therefore guide the design of adaptive electrocatalysts for clean energy conversions. RuO 2 is a promising anode catalyst for proton exchange membrane water electrolyzers but suffers from poor catalytic stability. Here the authors present a rhenium-doped RuO 2 with a unique dynamic electron accepting-donating that adaptively boosts activity and stability in acidic water oxidation.

Electrochemical carbon dioxide reduction to fuels presents one of the great challenges in chemistry. Herein we present an understanding of trends in electrocatalytic activity for carbon dioxide reduction over different metal catalysts that rationalize a number of experimental observations including the selectivity with respect to the competing hydrogen evolution reaction. We also identify two design criteria for more active catalysts. The understanding is based on density functional theory calculations of activation energies for electrochemical carbon monoxide reduction as a basis for an electrochemical kinetic model of the process. We develop scaling relations relating transition state energies to the carbon monoxide adsorption energy and determine the optimal value of this descriptor to be very close to that of copper. Identifying trends in electrocatalytic activity for carbon dioxide reduction can help with catalyst design, but are difficult to define. Here, the authors develop an electrochemical kinetic model of the process, identifying scaling relations relating transition state energies to CO adsorption energy on metal surfaces.

Pulmonary monitoring is crucial for the diagnosis and management of respiratory conditions, especially after the epidemic of coronavirus disease. Electrical impedance tomography (EIT) is an alternative non-radioactive tomographic imaging tool for monitoring pulmonary conditions. This review proffers the current EIT technical principles and applications on pulmonary monitoring, which gives a comprehensive summary of EIT applied on the chest and encourages its extensive usage to clinical physicians. The technical principles involving EIT instrumentations and image reconstruction algorithms are explained in detail, and the conditional selection is recommended based on clinical application scenarios. For applications, specifically, the monitoring of ventilation/perfusion (V/Q) is one of the most developed EIT applications. The matching correlation of V/Q could indicate many pulmonary diseases, e.g., the acute respiratory distress syndrome, pneumothorax, pulmonary embolism, and pulmonary edema. Several recently emerging applications like lung transplantation are also briefly introduced as supplementary applications that have potential and are about to be developed in the future. In addition, the limitations, disadvantages, and developing trends of EIT are discussed, indicating that EIT will still be in a long-term development stage before large-scale clinical applications.

The directional transformation of carbon dioxide (CO 2 ) with renewable hydrogen into specific carbon-heavy products (C 6+ ) of high value presents a sustainable route for net-zero chemical manufacture. However, it is still challenging to simultaneously achieve high activity and selectivity due to the unbalanced CO 2 hydrogenation and C–C coupling rates on complementary active sites in a bifunctional catalyst, thus causing unexpected secondary reaction. Here we report LaFeO 3 perovskite-mediated directional tandem conversion of CO 2 towards heavy aromatics with high CO 2 conversion (> 60%), exceptional aromatics selectivity among hydrocarbons (> 85%), and no obvious deactivation for 1000 hours. This is enabled by disentangling the CO 2 hydrogenation domain from the C-C coupling domain in the tandem system for Iron-based catalyst. Unlike other active Fe oxides showing wide hydrocarbon product distribution due to carbide formation, LaFeO 3 by design is endowed with superior resistance to carburization, therefore inhibiting uncontrolled C–C coupling on oxide and isolating aromatics formation in the zeolite. In-situ spectroscopic evidence and theoretical calculations reveal an oxygenate-rich surface chemistry of LaFeO 3 , that easily escape from the oxide surface for further precise C–C coupling inside zeolites, thus steering CO 2 -HCOOH/H 2 CO-Aromatics reaction pathway to enable a high yield of aromatics. The transformation of CO2 with renewable hydrogen into high-value products presents a sustainable route for net-zero chemical manufacture. Here the authors introduce a LaFeO3 perovskite-mediated tandem conversion of CO2, achieving remarkable performance by separating the CO2 hydrogenation and C-C coupling domains in the catalyst system.

The electrochemical conversion of carbon di-/monoxide into commodity chemicals paves a way towards a sustainable society but it also presents one of the great challenges in catalysis. Herein, we present the trends in selectivity towards specific dicarbon oxygenate/hydrocarbon products from carbon monoxide reduction on transition metal catalysts, with special focus on copper. We unveil the distinctive role of electrolyte pH in tuning the dicarbon oxygenate/hydrocarbon selectivity. The understanding is based on density functional theory calculated energetics and microkinetic modeling. We identify the critical reaction steps determining selectivity and relate their transition state energies to two simple descriptors, the carbon and hydroxide binding strengths. The atomistic insight gained enables us to rationalize a number of experimental observations and provides avenues towards the design of selective electrocatalysts for liquid fuel production from carbon di-/monoxide. Key mechanistic steps for selective CO (2) reduction over Cu into hydrocarbon versus oxygenated C 2 products are identified by atomistic and microkinetic modeling. Variations in C and OH binding are found to predict catalytic selectivity of materials.

We present a microkinetic model for CO (2) reduction (CO (2) R) on Cu(211) towards C 2 products, based on energetics estimated from an explicit solvent model. We show that the differences in both Tafel slopes and pH dependence for C 1 vs C 2 activity arise from differences in their multi-step mechanisms. We find the depletion in C 2 products observed at high overpotential and high pH to arise from the 2 nd order dependence of C-C coupling on CO coverage, which decreases due to competition from the C 1 pathway. We further demonstrate that CO (2) reduction at a fixed pH yield similar activities, due to the facile kinetics for CO 2 reduction to CO on Cu, which suggests C 2 products to be favored for CO 2 R under alkaline conditions. The mechanistic insights of this work elucidate how reaction conditions can lead to significant enhancements in selectivity and activity towards higher value C 2 products. CO 2 conversion to reduced products provides a use for greenhouse gases, but reaction complexity stymies mechanistic studies. Here, authors present a microkinetic model for CO 2 and CO reduction on copper, based on ab initio simulations, to elucidate pH’s impact on competitive reaction pathways.

Spontaneous monodispersion of reducible active species (e.g., Fe, Co) and their stabilization in reductive atmospheres remain a key challenge in catalytic syngas chemistry. In this study, we present a series of catalysts including spontaneously monodispersed and enriched Fe on ZnCr 2 O 4 . Deep investigation shows remarkable performance in the syngas-to-aromatic reaction only when monodispersed Fe coupled with a H-ZSM-5 zeolite. Monodispersed Fe increases the turnover frequency from 0.14 to 0.48 s −1 without sacrificing the record high selectivity of total aromatics (80–90%) at a single pass. The increased activity is ascribed to more efficient activation of CO and H 2 at oxygen vacancy nearest to the isolated Fe site and the prevention of carbide formation. Atomic precise characterization and theoretical calculations shed light on the origin and implications of spontaneous Fe monodispersion, which provide guidance to the design of next-generation catalyst for upgrading small molecules to synthetic fuels and chemicals. Spontaneous monodispersion of active species and their stabilization in reductive atmospheres remain a challenge in catalytic syngas chemistry. Here the authors demonstrate that syngas-to-aromatic conversion can be significantly accelerated by the spontaneously monodispersed Fe in ZnCr 2 O 4 spinel.

Metal hydrides are crucial intermediates in numerous catalytic reactions. Intensive efforts have been dedicated to constructing molecular metal hydrides, where toxic precursors and delicate mediators are usually involved. Herein, we demonstrate a facile pressure-induced methodology to generate a cost-effective heterogeneous electrocatalytic metal hydride surface for sustainable hydrogen transfer. Taking carbon dioxide (CO 2 ) electroreduction as a model system and zinc (Zn), a well-known carbon monoxide (CO)-selective catalyst, as a model catalyst, we showcase a homogeneous-type hydrogen atom transfer process induced by heterogeneous hydride surfaces, enabling direct hydrogenation pathways traditionally considered “prohibited”. Specifically, the maximal Faradaic efficiency for formate is enhanced by ~fivefold to 83% under ambient conditions. Experimental and theoretical analyses reveal that unlike the distal hydrogenation route for CO 2 to CO over pristine Zn, the Zn hydride surface enables direct hydrogenation at the carbon site of CO 2 to form formate. This work provides a promising material platform for sustainable synthesis. The authors demonstrate a facile pressure-induced methodology to generate a cost-effective heterogeneous electrocatalytic metal hydride surface for sustainable hydrogen transfer.