'Accelerated' Deactivation of Carbon Nitride Photocatalyst for Solar Hydrogen Evolution

Carbon nitride photocatalysts are among the most studied candidates for efficient solar hydrogen (H₂) production due to their abundance of precursors, suitable bandgap, and visible light utilization. However, the polymeric nature of carbon nitride materials raises concerns regarding the self-decomposition during photocatalytic redox processes. Yet, the operational stability of carbon nitride photocatalysts for solar H₂ production remains under-explored. Here we evaluate the photostability of carbon nitride photocatalysts with platinum (Pt) as the co-catalyst for solar H₂ evolution and significant deactivation of this photocatalyst is observed under'accelerated' testing conditions. It is demonstrated that the detachment of the Pt co-catalyst on the surface of carbon nitride is the major reason for this deactivation, which can be attributed to a synergistic effect of photo-corrosion and mechanical stirring. The photo-corrosion weakens the interfacial bonding between carbon nitride and Pt co-catalyst, while continuous collisions from the mechanical stirring promote the detachment of co-catalysts from the surface of carbon nitride. These understandings provide insights into the rational design of photocatalysts and photocatalytic systems for improved operational stability.