Single-Crystalline Mesoporous Palladium and Palladium-Copper Nanocubes for Highly Efficient Electrochemical CO₂ Reduction

Mesoporous single crystals have unique potential in catalysis, but remain unexplored owing to the enormous synthetic challenge that they pose. Herein, we report a facile soft-template method to prepare palladium (Pd) and Pd alloy nanocubes with single-crystallinity and abundant mesoporosity. The successful formation of these exotic nanostructures essentially relies on the cointroduction of cetyltrimethylammonium chloride as the surfactant template and extra Cl⁻ ions as the facet-selective capping agent under well controlled experimental conditions. Thanks to their large surface areas and penetrating mesoporous channels, our products exhibit a great performance for electrochemical CO₂ reduction. The best sample from alloying palladium with copper enables the efficient formate production with high selectivity (90∼100%) over a broad potential range, and great stability even under the working potential as cathodic as −0.5 V versus a reversible hydrogen electrode. These performance metrics are far superior to previous Pd-based materials, and underscore the structural advantages of our products.