Restraining Lattice Oxygen Escape Improves The Valence Stability Of Cu⁺ During CO₂RR

The efficient reduction of carbon dioxide（CO₂）into a value-added fuel and feedstock through renewable electricity provides a way towards zero emissions and carbon neutrality.Copper oxides（Cu O_x）catalysts can produce C₂₊products with electrocatalytic reduction of carbon dioxide（CO₂RR）,while they still suffer from fast deactivation rate and poor selectivity.Meanwhile,the deactivation mechanism of the active Cu⁺species is still unclear,which seriously hinders the development of advanced Cu O_xbased catalysts.A large number of studies have found that under electrochemical conditions,Cu⁺species will be unavoidably reduced,leading to a decrease in the selectivity of catalysts.Therefore,how to effectively improve the stability of Cu⁺species in copper-based catalysts and highly selective production of target products are the main challenges in the application of copper-based catalysts in CO₂RR.In this paper,we explore an effective strategy of stabilizing the active Cu⁺sites to boost the CO₂RR performance based on a molecular-level understanding of the metal sites dependent selectivity and stability of copper oxides-based catalysts.The mechanism of medium valence state stability was studied by changing the electronic structure of catalyst by different methods.Specific work is as follows:We have successfully prepared the B doped Cu₂O（B-Cu₂O）catalyst.The incorporated B can effectively enhance the stability of lattice oxygen and the sites of Cu⁺,and improve the selectivity of C₂H₄products.The C₂H₄/CO ratio of B-Cu₂O catalyst is 2.5 at-1.2 V vs reversible hydrogen electrode,which is3.5-fold higher than that of undoped Cu₂O catalyst.Meanwhile,theoretical calculations and experiments revealed that the doped B atoms redistributes the charge density of Cu₂O,which strengthens the hybridization of Cu and O atoms and inhibits the migration of lattice oxygen.This work effectively stabilizes the Cu⁺site by improving the stability of lattice oxygen,and improves the selectivity for C₂H₄products.We prepared MoS₂ decorated Cu₂O catalyst（Cu₂O-Mo S₂）.The introduced Mo S₂into Cu₂O can effectively regulate the electron localization in the catalyst,resulting in enhanced stability of lattice oxygen and Cu⁺site,thus improving the selectivity of C₂H₄.As a result,at-1.2 V vs reversible hydrogen electrode,Cu₂O-Mo S₂attain the highest 22.1%Faradaic efficiency for C₂H₄production,much large than that of Cu₂O catalyst（11.7%）.The superior performance of Cu₂O-Mo S₂is attributed to the easier charge transfer from Mo S₂to Cu₂O,thus improving the stability of the Cu⁺sites.Both the experimental results and theoretical calculations show that Cu₂O-Mo S₂catalyst can effectively reduce the attack of electrons on Cu-O bonds,which consequently stabilizes of lattice oxygen and Cu⁺sites.Based on this,we proposed the strategy of“electron direction regulation”to effectively improve the stability of lattice oxygen and Cu⁺sites.In summary,we demonstrated that element doping and electronic regulation can effectively stabilize the lattice oxygen and active sites of Cu⁺of Cu₂O catalyst,thus improving the catalytic selectivity of CO₂RR.This thesis provides useful conclusion and method obtained,which can be extended to the design and work of the valence stability of other substances.