Self-Poisoning by C2 Products in CO2 Photoreduction Using a Phosphorus-Doped Carbon Nitride with Nitrogen Vacancies

Understanding the reaction and deactivation mechanism of CO2 photoreduction is critical to the carbon-neutral economy. Here, we report a self-poisoning effect in CO2 photoreduction accompanied by C2 production. With phosphorus-doping and nitrogen-vacancy engineering, the CO2 photoreduction reactivity on carbon nitride can be significantly enhanced with a considerable yield of C2. Nevertheless, the stability of this catalyst decreases with the enhanced C2 production. The deactivation originates from the rigid bonding between the catalysts and C2 products, slowing down the desorption process and poisoning the catalysts. This work demonstrates the opposite role of defect engineering in the activity and stability of CO2 photoreduction, which may provide insights into a highly reactive and durable C2 catalyst design.