Modulated Solution Plasma Environment over Modified-C ₃ N ₄ /TCPP Polymers for Sustainable H ₂ O ₂ Production

Nonmetallic polymers are promising materials for the production of H2O2 by O2 reduction reactions in water, since they activate oxygen to reactive oxygen species under photo/electrical excitation. However, the slow kinetics of water activation restricts the rate of H2O2 production. Solution plasma technology has emerged as a promising strategy, as it effectively activates water molecules, thereby facilitating the water oxidation process while simultaneously introducing an oxygen reduction pathway that consumes H+ ions for efficient H2O2 production. Here, we loaded meso-tetra(4-carboxyphenyl) porphyrin (TCPP) with photosensitizing properties onto cyano-modified carbon nitride (CCN) to form π–π-stacked solution plasma catalysts that exhibited excellent H2O2 activity. The H+ concentration in the CCN/TCPP polymer solution decreased by a factor of 104 after 1 h of discharge compared to the noncatalyst system, indicating that the catalyst promoted the O2 reduction reaction. The CCN/TCPP accumulated 32 mM H2O2 with an energy conversion efficiency of 0.91%. The lower intersystem crossing (ISC) energy barrier of CCN/TCPP allows CCN/TCPP and O2 to produce 1O2 at a faster energy transfer rate to consume H+ from the discharge and produce H2O2. This study widens the design of solution plasma catalysts for the production of H2O2 and provides an effective strategy for the sustainable development of solution plasma catalytic technology.