Thermal Engineering Unlocks Prolonged Hot-Carrier Lifetime in Potassium-Doped Carbon Nitride for Sustainable...

In response to sustainable development requirements, this work prepared a novel potassium-doped graphitic carbon nitride via a simple two-step calcination method and applied it in the photocatalytic degradation of phenol. After secondary calcination, the potassium-doped carbon nitride exhibited stronger K-N bonding and an increased specific surface area due to the developed pore structure. Moreover, the introduction of defect states significantly enhanced the charge transport and carrier separation efficiency. Femtosecond transient spectroscopy revealed a 69-fold increase in hot carrier lifetime, while theoretical calculations indicated strong interfacial adsorption capacity for both phenol and oxygen molecules, leading to a 28-fold improvement in the phenol degradation rate. Furthermore, the material demonstrated high cycling stability, lower energy consumption compared to pristine g-C₃N₄, reduced environmental impact relative to other modification methods (as supported by LCA), and a simple preparation routeall of which contributed to its superior engineering potential, environmental friendliness, and sustainability for water treatment. This work provides a balanced research paradigm and platform that integrate performance optimization and engineering feasibility studies for water purification applications.