Hierarchically porous Au nanostructures with interconnected channels for efficient mass transport in electrocatalytic CO2 reduction

Electrocatalytic CO2 reduction is a promising way to provide renewable energy from gaseous CO2. The development of nanostructures improves energy efficiency and selectivity for value-added chemicals, but complex nanostructures limit the CO2 conversion rates due to poor mass transport during vigorous electrolysis. Herein, we propose a three-dimensional (3D) hierarchically porous Au comprising interconnected macroporous channels (200-300 nm) and nanopores (similar to 10 nm) fabricated via proximity-field nanopatterning. The interconnected macropores and nanopores enable efficient mass transport and large active areas, respectively. The roles of each pore network are investigated using reliable 3D nanostructures possessing controlled pore distribution and size. The hierarchical nanostructured electrodes show a high CO selectivity of 85.8% at a low overpotential of 0.264 V and efficient mass activity that is maximum 3.96 times higher than that of dealloyed nanoporous Au. Hence, the systematic model study shows the proposed hierarchical nanostructures have important value in increasing the efficiency of expensive Au.