It is highly desired yet challenging to steer the CO 2 electroreduction reaction (CO 2 ER) toward ethanol with high selectivity, for which the evolution of reaction intermediates on catalytically active sites holds the key. Herein, we report that K doping in Cu 2 Se nanosheets array on Cu foam serves as a versatile way to tune the interaction between Cu sites and reaction intermediates in CO 2 ER, enabling highly selective production of ethanol. As revealed by characterization and simulation, the electron transfer from K to Se can stabilize Cu I species which facilitate the adsorption of linear *CO L and bridge *CO B intermediates to promote CÀ C coupling during CO 2 ER. As a result, the optimized K 11.2% -Cu 2 Se nanosheets array can catalyze CO 2 ER to ethanol as a single liquid product with high selectivity in a potential area from À 0.6 to À 1.2 V. Notably, it offers a Faradaic efficiency of 70.3 % for ethanol production at À 0.8 V with as is stable for 130 h.

It is an ongoing pursuit for researchers to precisely control the catalyst’s surface for high-performance CO2 electrochemical reduction (CO2ER). In this work, CuO mesoporous nanosheets (CuO MNSs) with rough edges decorated by small Ag nanoparticles (Ag NPs) with a tunable amount of Ag were synthesized on a Cu foil at normal atmospheric temperature through two-step solution-phase reactions for CO2ER to CO. In this special Ag NPs/CuO MNSs heterostructure, the mesoporous CuO NSs with rough edges favored gas infiltration, while decorated Ag NPs expanded the active sites for CO2 molecule adsorption. Ag NPs endowed Ag NPs/CuO MNSs with good electrical conductivity and promoted the adsorbed CO2 molecules to obtain electrons from the catalyst. Especially, the Ag–CuO interface stabilized the *COOH intermediate with strong bonding, which is important in boosting CO2ER to CO. The optimal Ag1.01%/CuO can catalyze CO2ER to CO with a Faradaic efficiency of 91.2% and a partial current density of 10.5 mA cm–2 at −0.7 V. Moreover, it exhibited prominent catalytic stability, retaining 97.8% of the initial current density and 97.6% of the original Faradaic efficiency for CO after 12 h of testing at −0.7 V. Notably, the Faradaic efficiency of CO on Ag1.01%/CuO can retain over 80% in the potential area from −0.6 to −0.9 V, embodying its high selectivity for CO. This work develops precious metal/metal oxide heterostructures with a low precious metal loading for efficacious CO2ER to CO and beyond.

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Rare studies have been performed to trace the mineral elements in Dendrobium officinale. In this study, we aim to trace the mineral elements in D. officinale collected from ten geographical locations in China. ICP-MS system was used for simultaneous determination of mineral elements. Principal component analysis was performed using the obtained data in the quantification of mineral contents. Cluster analysis was performed using the Ward’s method. Several of essential microelments were detected in D. officinale, including ferrum (Fe), manganese (Mn), zinc (Zn), chromium (Cr), nickel (Ni) and vanadium (V). Among these elements, three elements (i.e. Fe, Mn and Zn) were highly and simultaneously detected in the D. officinale collected from the ten locations. The level of Ni was positively associated with that of Zn (r = 0.986, P < 0.01). The level of titanium (Ti) was positively associated with that of V (r = 0.669, P < 0.05), and negatively associated with Cr (r = −0.710, P < 0.05). In addition, the level of Mn was positively associated with that of barium (r = 0.749, P < 0.05). Further, the level of Fe was positively associated with that of Ni (r = 0.664, P < 0.05), Zn (r = 0.742, P < 0.05), and rare earth elements (r = 0.847, P < 0.01), respectively. Three eigenvalues explained about 86.60 % of the total variance, which contributed significantly to the explanation of cumulative variance. Cluster analysis indicated the cultivars were categorized into 3 clusters. Ni, Zn, Fe, Cr, Ti and rare earth elements were designated as the characteristic elements. Cultivars collected from Yulin, Menghai, and Shaoguan ranked the top 3 in the comprehensive scores, indicating the content of the mineral elements was comparatively higher in these locations.

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It is highly desired yet challenging to steer the CO 2 electroreduction reaction (CO 2 ER) toward ethanol with high selectivity, for which the evolution of reaction intermediates on catalytically active sites holds the key. Herein, we report that K doping in Cu 2 Se nanosheets array on Cu foam serves as a versatile way to tune the interaction between Cu sites and reaction intermediates in CO 2 ER, enabling highly selective production of ethanol. As revealed by characterization and simulation, the electron transfer from K to Se can stabilize Cu I species which facilitate the adsorption of linear *CO L and bridge *CO B intermediates to promote CÀ C coupling during CO 2 ER. As a result, the optimized K 11.2% -Cu 2 Se nanosheets array can catalyze CO 2 ER to ethanol as a single liquid product with high selectivity in a potential area from À 0.6 to À 1.2 V. Notably, it offers a Faradaic efficiency of 70.3 % for ethanol production at À 0.8 V with as is stable for 130 h.

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