Determining the three-dimensional structure of a protein in living cells remains particularly challenging. We demonstrated that the integration of site-specific tagging proteins and GPS-Rosetta calculations provides a fast and effective way of determining the structures of proteins in living cells, and in principle the interactions and dynamics of protein-ligand complexes.
The formation of (bi)carbonates is a pressing issue for
CO2 electroreduction in neutral or alkaline solutions.
It adversely
causes low single-pass conversion efficiency as a result of (bi)carbonate
crossover, as well as limited device lifetimes as a result of (bi)carbonate
precipitation at the cathode. One emerging solution to circumvent
this challenge is conducting the reaction in acids. To this end, we
here demonstrate an acid-fed membrane electrode assembly (MEA) for
CO2 electroreduction to CO. A diluted electrolyte with
an H+ to Cs+ ratio of 1:1 and a relatively low
current density are optimal conditions to achieve high CO Faradaic
efficiencies. A relatively high H+ versus Cs+ ratio offers high electrocatalytic activities. By systematically
evaluating the impact of H+ and Cs+ concentration
on the electrochemical performance, we uncover the essential role
of the balance between the rates of (bi)carbonate formation and H+ diffusion in determining the selectivity and activity. As
a result, we report a CO partial current density of ∼105 mA
cm–2 at an ∼4 V cell voltage, a near-doubled
activity toward CO compared to a neutral MEA at a similar voltage.
Under the optimal conditions for long-term operation, our acid-fed
membrane electrode assembly is capable of delivering a CO Faradaic
efficiency of ∼80%, an extraordinary single-pass conversion
efficiency of ∼90% (about twice that of neutral MEA), and a
50 h long-term stability notably superior to those in previous reports.
The behaviours of hydrogen and helium in tungsten are vitally important in fusion research because they can result in the degradation of the material. In the present work, we carry out density-functional theory calculations to investigate the clustering of hydrogen and helium atoms at interstitial sites, vacancy and small vacancy clusters (Vac m , m = 2, 3), and the influence of hydrogen and helium on vacancy evolution in tungsten. We find that hydrogen atoms are extremely difficult to aggregate at interstitial sites to form a stable cluster in tungsten. However, helium atoms are energetically favourable to cluster together in a close-packed arrangement between (1 1 0) planes forming helium monolayer structure, where the helium atoms are not perfectly in one plane. Both hydrogen and helium prefer to aggregate stably in vacancy and small vacancy cluster forming Vac m X n (X = H, He). The concentrations of Vac m H n (m = 1) clusters relative to temperature are evaluated through the law of mass action. The present calculations also show that the emission of a 1 1 1 dumbbell self-interstitial atom (SIA) from He n to form VacHe n and from VacHe n to form Vac 2 He n may take place for n > 5 and n > 9, respectively. According to the present results, we predict that a helium monolayer structure could nucleate for He atom platelet lying on (1 1 0) plane in tungsten, and the helium platelet formation on (1 1 0) plane in molybdenum observed by the experiment may be due to the initial monolayer arrangement of He atoms at interstitial sites. Meanwhile, our results contribute to the understanding for nucleation and the development of the voids and blisters in tungsten that are observed in the experiments.
There is a lack of straightforward methods to prepare high‐quality bismuthene nanosheets, or, even more challengingly, to grow their arrays due to the low melting point and high oxophilicity of bismuth. This synthetic obstacle has hindered their potential applications. In this work, it is demonstrated that the galvanic replacement reaction can do the trick. Under well‐controlled conditions, large‐area vertically aligned bismuthene nanosheet arrays are grown on Cu substrates of various shapes and sizes. The product features small nanosheet thickness of two to three atomic layers, large surface areas, and abundant porosity between nanosheets. Most remarkably, bismuthene nanosheet arrays grown on Cu foam can enable efficient CO2 reduction to formate with high Faradaic efficiency of >90%, large current density of 50 mA cm−2, and great stability.
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