Efficient CO₂ Reduction Reaction on Cu-Decorated Biphenylene

Developing efficient electrocatalysts for CO₂ reduction into value-added products is crucial for a green economy. Inspired by the recent experimental synthesis of biphenylene (BPH) and the excellent catalytic activity of copper dispersed on two-dimensional (2D) materials, we chose to systematically investigate the pristine, defective, and Cu-decorated BPH for the electrocatalytic CO₂ reduction to value-added hydrocarbons. It is observed that the CO₂ molecules bind weakly to the pristine BPH, indicating their chemical inertness. Carbon single-vacancy defects facilitate CO₂ adsorption with a strong binding energy (E_b) of −3.23 eV, detrimental to the CO₂ reduction reaction (CRR) mechanism. We have further 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 a ΔE_b of −0.52 eV. The CRR mechanism is investigated using two pathways beginning with two different initial states, formate (*OCOH) and carboxylic (*COOH). The formate pathway confirms the conversion of *OCOH to *HCOOH with the rate-limiting potential (U_L) of 0.39 eV for the production of HCOOH, while for the carboxylic pathway, the conversion of *COH to *CHOH has a U_L of 0.32 eV, eventually producing CH₃OH. Our findings highlight the role of Cu-BPH as an efficient SAC for CO₂ catalytic activity to C1 products, as compared to the state-of-the-art Cu, and holds promise as an electrocatalyst for CRR.