Efficient Electrochemical CO2 Reduction Reaction over Cu-decorated Biphenylene

Developing efficient electrocatalysts for CO₂ reduction into value-added products is crucial for the green economy. Inspired by the recent synthesis of Biphenylene (BPH), we have systematically investigated pristine, defective, and Cu-decorated BPH as an electrocatalyst for the CO₂ reduction reactions (CRR). Our first-principles calculations show the CO₂ molecules weakly interact with the pristine BPH surface while defective BPH facilitates the CO₂ adsorption with a binding energy (Eb) of -3.22 eV, indicating the detrimental process for the CRR on the surface of both systems. Furthermore, we have investigated the binding energy and kinetic stability of Cu-decorated BPH as a single-atom-catalyst (SAC). The molecular dynamics simulations confirm the kinetic stability, revealing that the Cu-atom avoids agglomeration under low metal dispersal conditions. The CO₂ molecule gets adsorbed horizontally on the Cu-BPH surface with Eb of -0.52 eV. The CRR mechanism is investigated using two pathways beginning with two different initial intermediate states, formate (^*OCOH) and the carboxylic (^*COOH) pathways. The formate pathway confirms the conversion of ^*OCOH to ^*HCOOH with the rate-limiting potential (UL) of 0.57 eV for the production of HCOOH, while for the carboxylic pathway, the conversion of ^*COH to ^*CHOH has UL of 0.49 eV for the production of CH₃OH. We have also investigated the effect of protons using charged hydrogen pseudopotential, which hints towards the possible formation of CH₃OH as fuel. Our findings propose Cu-BPH as an efficient single-atom catalyst for CO₂ conversion compared to the well-known Cu metal.