Defect‐Enriched Hollow Porous Carbon Nanocages Enable Highly Efficient Chlorine Evolution Reaction

Metal‐free carbon‐based catalysts are crucial for the electrocatalytic chlorine evolution reaction (CER) to reduce the usage of noble metals and industrial cost. However, the corresponding catalytic activity of high overpotential and low durability hinders their wide application. Here, a hollow porous carbon (HPC) nanocage with a controlled oxygen electronic state around designed carbon defects for CER activity is reported. Alkali etching can bring defects in zeolite with a hollow structure. In a hard template strategy, the type of carbon defects is directly related to etching degree of the zeolite template. More importantly, the oxygen atoms can be “borrowed” from the zeolite framework by the defective carbon. The electron density around unsaturated O atoms can be decreased on the minor defects in carbon compared with that on large defects which is favorable for the adsorption of Cl−. Consequently, the as‐synthesized HPC nanocages with minor defects show excellent electrocatalytic performance for CER with a low overpotential of 94 mV at current density of 10 mA cm−2 with good stability, which is superior to the commercial precious metal catalyst of dimensionally stable anode (DSA), and the best in the reported carbon materials. The designed carbon materials provide an option for metal‐free industrial catalysts with significant CER activities. Hollow porous carbon (HPC) nanocages with a controlled oxygen electronic state around the designed carbon defects are fabricated through a hard template strategy for the electrocatalytic chlorine evolution reaction (CER). The electron density around the unsaturated O atoms can be decreased on the minor defects in carbon which is favorable for the adsorption of Cl−. The optimum HPC nanocages with lowest defective degree show excellent electrocatalytic performance for the CER.