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Molecular tuning of CO2-to-ethylene conversion 期刊论文
NATURE, 2020, 577 (7791) : 509-+
作者:  Li, Fengwang;  39;Brien, Colin P.
收藏  |  浏览/下载:37/0  |  提交时间:2020/07/03

The electrocatalytic reduction of carbon dioxide, powered by renewable electricity, to produce valuable fuels and feedstocks provides a sustainable and carbon-neutral approach to the storage of energy produced by intermittent renewable sources(1). However, the highly selective generation of economically desirable products such as ethylene from the carbon dioxide reduction reaction (CO2RR) remains a challenge(2). Tuning the stabilities of intermediates to favour a desired reaction pathway can improve selectivity(3-5), and this has recently been explored for the reaction on copper by controlling morphology(6), grain boundaries(7), facets(8), oxidation state(9) and dopants(10). Unfortunately, the Faradaic efficiency for ethylene is still low in neutral media (60 per cent at a partial current density of 7 milliamperes per square centimetre in the best catalyst reported so far(9)), resulting in a low energy efficiency. Here we present a molecular tuning strategy-the functionalization of the surface of electrocatalysts with organic molecules-that stabilizes intermediates for more selective CO2RR to ethylene. Using electrochemical, operando/in situ spectroscopic and computational studies, we investigate the influence of a library of molecules, derived by electro-dimerization of arylpyridiniums(11), adsorbed on copper. We find that the adhered molecules improve the stabilization of an '  atop-bound'  CO intermediate (that is, an intermediate bound to a single copper atom), thereby favouring further reduction to ethylene. As a result of this strategy, we report the CO2RR to ethylene with a Faradaic efficiency of 72 per cent at a partial current density of 230 milliamperes per square centimetre in a liquid-electrolyte flow cell in a neutral medium. We report stable ethylene electrosynthesis for 190 hours in a system based on a membrane-electrode assembly that provides a full-cell energy efficiency of 20 per cent. We anticipate that this may be generalized to enable molecular strategies to complement heterogeneous catalysts by stabilizing intermediates through local molecular tuning.


Electrocatalytic reduction of CO2 over copper can be made highly selective by '  tuning'  the copper surface with adsorbed organic molecules to stabilize intermediates for carbon-based fuels such as ethylene


  
Variability in the analysis of a single neuroimaging dataset by many teams 期刊论文
NATURE, 2020
作者:  Liu, Jifeng;  Soria, Roberto;  Zheng, Zheng;  Zhang, Haotong;  Lu, Youjun;  Wang, Song;  Yuan, Hailong
收藏  |  浏览/下载:49/0  |  提交时间:2020/07/03

Data analysis workflows in many scientific domains have become increasingly complex and flexible. Here we assess the effect of this flexibility on the results of functional magnetic resonance imaging by asking 70 independent teams to analyse the same dataset, testing the same 9 ex-ante hypotheses(1). The flexibility of analytical approaches is exemplified by the fact that no two teams chose identical workflows to analyse the data. This flexibility resulted in sizeable variation in the results of hypothesis tests, even for teams whose statistical maps were highly correlated at intermediate stages of the analysis pipeline. Variation in reported results was related to several aspects of analysis methodology. Notably, a meta-analytical approach that aggregated information across teams yielded a significant consensus in activated regions. Furthermore, prediction markets of researchers in the field revealed an overestimation of the likelihood of significant findings, even by researchers with direct knowledge of the dataset(2-5). Our findings show that analytical flexibility can have substantial effects on scientific conclusions, and identify factors that may be related to variability in the analysis of functional magnetic resonance imaging. The results emphasize the importance of validating and sharing complex analysis workflows, and demonstrate the need for performing and reporting multiple analyses of the same data. Potential approaches that could be used to mitigate issues related to analytical variability are discussed.


The results obtained by seventy different teams analysing the same functional magnetic resonance imaging dataset show substantial variation, highlighting the influence of analytical choices and the importance of sharing workflows publicly and performing multiple analyses.


  
Model parameter-related optimal perturbations and their contributions to El Nino prediction errors 期刊论文
CLIMATE DYNAMICS, 2019, 52: 1425-1441
作者:  Tao, Ling-Jiang;  Gao, Chuan;  Zhang, Rong-Hua
收藏  |  浏览/下载:24/0  |  提交时间:2019/04/09
Intermediate coupled model  CNOP approach  Model parameters  El Nino predictability  
Measuring unified efficiency of Chinese fossil fuel power plants: Intermediate approach combined with group heterogeneity and window analysis 期刊论文
ENERGY POLICY, 2018, 123: 8-18
作者:  Sun, Chuanwang;  Liu, Xiaohong;  Li, Aijun
收藏  |  浏览/下载:23/0  |  提交时间:2019/04/09
Unified Efficiency  DEA Environmental Assessment  Fossil Fuel Power Plants  Carbon Dioxide Emissions  Intermediate Approach  Group and Meta Frontier