Dalian University of Technology Guo News, Hong Yang, Hou Jungang and othersA bimetallic photocatalyst formed by atomically dispersed in-cu anchored on polymeric carbon nitride (IncU PCN) is reportedThe catalyst catalyzes CO2 photoreduction to achieve 28Excellent ethanol yield of 5 mol·g-1·h-1 and high selectivity of 92%. Essentially, the In-Cu interaction enhances charge separation by accelerating charge transfer from PCNs to metal sites. In also transfers electrons to adjacent Cu via the Cu-N-In bridge, thereby increasing the electron density at the active site of Cu;In addition, the in-cu bimetal site promotes the adsorption of *Co intermediates and reduces the energy barrier of C-C coupling.
DFT calculates Gibbs free energy plots of CO2 photoreduction on Incu PCN, Cu PCN, and IN PCN. Gibbs free energy calculations show that the C-C bond is directly coupled by Co* to form *CoCo. As revealed, the formation of *COOH is Incu PCN (δg = +1.).20EV) and in PCN (δg = +1.).86EV). In contrast, the formation of *Coch2OH is a rate-determining step on the Cu PCN (δg = +1.).98ev）。On Incu PCN, *Co(ΔG=0.).45EV) and hydrogenation of *CoCo to *CoCoH (δg = 0.).61EV) are endothermic processes;Subsequently, the basic steps related to the reduction of *Cocoh to *CHCH2OH are exothermic processes. However, the *CHCH2OH *CH3CH2OH ethanol after that is an endothermic step (δg = +1.).09ev）。
On the other hand,On Cu PCN, *Co undergoes dimerization to form *CoCo. However, the Gibbs free energy is higher than that of the *CO dimerization catalyzed by the Incu PCN。The hydrogenation of *CoCo*Coch *Cochoh is an exothermic process, while the hydrogenation step from *Cochoh to *Coch2OH is endothermic and has the highest energy (δg = +1.).98ev）。
This is followed by several energy-reducing reaction processes from *Coch2OH to *CH2CH2OH. The total Gibbs energy increase for the final endothermic step of CH2CH2OH *CH3CH2OH ethanol is similar to that on IncU PCN. Finally,On In PCN, *CO intermediates tend to desorb as CO on IN PCN, rather than binding to form *CoCo as on Incu PCN and Cu PCN。This lack of C-C coupling results in very, extremely low ethanol yields obtained in CO2 photoreduction tests.
hainan shi, haozhi wang et al. atomically dispersed indium-copper dual-metal active sites promoting c–c coupling for co2 photoreduction to ethanol. angew. chem. int. ed. 2022, e202208904