Oxygen Functionalized Copper Nanoparticles for Solar-Driven Conversion of Carbon Dioxide to Methane
Mohammadreza Esmaeilirad, Alireza Kondori, Boao Song, Andrés Ruiz Belmonte, Jialiang Wei, Kamil Küçük, Shubhada Mahesh Khanvilkar, Erin Efimoff, Wei Chen, Carlo U. Segre, Reza Shahbazian‐Yassar, Mohammad Asadi
Abstract
Solar conversion of carbon dioxide (CO2) into hydrocarbon fuels offers a promising approach to fulfill the world’s ever-increasing energy demands in a sustainable way. However, a highly active catalyst that can also tune the selectivity toward desired products must be developed for an effective process. Here, we present oxygen functionalized copper (OFn-Cu) nanoparticles as a highly active and methane (CH4) selective catalyst for the electrocatalytic CO2 reduction reaction. Our electrochemical results indicate that OFn-Cu (5 nm) nanoparticles with an oxidized layer at the surface reach a maximum CH4 formation current density and turnover frequency of 36.24 mA/cm2 and of 0.17 s–1 at the potential of −1.05 V vs RHE, respectively, exceeding the performance of existing Cu and Cu-based catalysts. Characterization results indicate that the surface of the OFn-Cu nanoparticles consists of an oxygen functionalized layer in the form of Cu2+ (CuO) separated from the underneath elemental Cu by a Cu+ (Cu2O) sublayer. Density functional theory calculations also confirm that presence of the O site at the CuO (101) surface is the main reason for the enhanced activity and selectivity. Using this catalyst, we have demonstrated a flow cell with an active area of 25 cm2 that utilizes solar energy to produce 7.24 L of CH4 after 10 h of continuous process at a cell power density of 30 mW/cm2.