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Advanced energy materials: hybrid SP band modulates the selectivity of CO2 electroreduction

wallpapers News 2020-10-18
As a promising strategy electrochemical carbon dioxide reduction (ecrr) can not only avoid the increase of carbon dioxide emissions but also help the preparation of high value-added chemicals fuels. In addition ecrr can be driven by renewable energy which shows good economic benefits great practical value. For the transition metal based electrocatalysts with high carbon monoxide selectivity the inherent linear relationship limits the flexible control of the active intermediate adsorption product selectivity so it is difficult to achieve further improvement of catalytic activity. Interestingly non-metallic carbon based materials have shown adaptability to various electroreduction pathways which may be due to the absence of d-orbitals in carbon based materials thus naturally breaking the limitation of scaling relationship. Inspired by the controllable selectivity of carbon based electrocatalysts the utilization of S P bs may be an effective strategy to control the selectivity. In addition the preparation of high-quality porous electrocatalyst without additives is also important for the improvement of carbon dioxide reduction efficiency.

Professor Hou Jungang others of Dalian University of technology recently prepared porous sulfur modified cadmium electrocatalyst. The hybrid SP b composed of double coordination sites can catalyze the electrochemistry of CO2 to CO realizing the regulation of selectivity activity. The authors have designed developed a simple liquid phase synthesis method to prepare porous sulfur modified cadmium (P-CD | s) structure which can be widely applied to the preparation of a series of porous single metal or bimetallic sulfur-containing electrocatalysts. X-ray photoelectron spectroscopy extended X-ray absorption fine structure spectroscopy show that the amorphous P-CD | s structure consists of four coordinated cds4 units. Compared with unmodified cadmium P-CD | s has higher CO selectivity which indicates that sulfur dopant can make the product transform from formic acid to Co. Electrochemical measurements show that the current density of P-CD | s reaches 89.8 Ma cm-2 at − 0.80 V (relative to reversible hydrogen electrode). The significant increase in activity is partly due to the unique porous structure which contributes to the increase of active area rapid mass transfer. The finite element simulation shows that the porous structure promotes the increase of local pH the inhibition of hydrogen evolution side reaction to a great extent. The combination of in-situ Raman spectroscopy attenuated total reflection surface enhanced infrared absorption spectroscopy X-ray photoelectron spectroscopy with theoretical calculation reveals that cadmium cation sulfur anion act as synergistic active sites which promote the bridge site adsorption of * COOH intermediate the formation of Co. The calculations of the projected density of States molecular orbitals show that the covalently hybridized CDs 5S 4P s 3P bs transfer electrons from the surface to the empty anti bond π * orbital of CO2 which greatly promotes the formation of CO2 radicals the stabilization of intermediates. This work not only provides insight into the regulation of the electronic structure of nanomaterials the selectivity of carbon dioxide reduction products but also develops a simple strategy to prepare highly porous electrocatalysts.

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