Spin-Enhanced C-C Coupling in CO_(2)Electroreduction with Oxide-Derived Copper

Electrocatalytic reduction of carbon dioxide(CO_(2))to multicarbon(C2+)products involves intricate multiple protons and electron transfer of C-C coupling,which is dictated by not only the intrinsic reactivity but also the spin states of electrons in the catalyst.Here,we observe spin-enhanced CO_(2)reduction(CO_(2)RR)electrocatalytic activity on an oxidederived copper(OD-Cu)catalyst due to the existence of a specific Cu*site that carried the magnetic moments.Due to the correlation of magnetic and catalytic properties in OD-Cu,the current density through the OD-Cu electrode increases by nearly 10%at 350 mT.The field strength and angle dependence of such magnetic field effect(MFE),together with the time-resolved measurements proved that it originated from the alignment of magnetic moments on Cu*sites.The MFE on the electrocatalytic process enabled an enhancement(up to 15%)of the CO_(2)RR Faradaic efficiency using the OD-Cu catalyst.Importantly,the enhancement was attributed to the spinantiparallel alignment of electrons to promote C-C coupling on asymmetric Cu*-Cu sites;consequently,the optimal bias was reduced by∼0.2 V under the magnetic field for C2 products with Faradaic efficiency>30%and selectivity>75%.Our work uncovers a new paradigmfor spin-enhanced catalysis applicable to a broad range of chemical reactions involving spin singlet products.

Integration of resonant band with asymmetry in ferroelectric tunnel junctions

We propose that the asymmetry-induced tunneling electroresistance(TER)effect in a ferroelectric tunnel junction(FTJ)could be improved by integrating a polarization-controlled resonant band.Using first-principles calculations and a quantum-mechanical tunneling model,we studied an asymmetric FTJ SrRuO_(3)/BaTiO_(3)/SrTiO_(3)/SrRuO_(3).The resonant band is integrated into this FTJ by two atomic layers of BaSnO_(3)embedded in the barrier.In the elaborated FTJ SrRuO_(3)/BaTiO_(3)/BaSnO_(3)/SrTiO_(3)/SrRuO_(3),both resonant band and asymmetry work together.For one polarization direction,the BaSnO_(3)and SrTiO_(3)dielectric layers work together as barriers to provide considerable efficient barrier height for direct tunneling and lead to large tunneling resistance.For the opposite polarization,the BaSnO_(3)layer serves as a quantum well to induce resonant tunneling across the barrier and considerably reduces the tunneling resistance of the ON state.The integration of resonant band with asymmetry may provide a more efficient and applicable way to further improve the functionalities of FTJs.