Active-Site Photothermal Energy Utilization in PET Depolymerization

Photothermal catalysis offers a promising strategy for plastic recycling, yet how photothermal energy is delivered and utilized at catalytic sites remains poorly understood. Herein, we uncover a pronounced activity reversal during photothermal depolymerization of polyethylene terephthalate (PET) by regulating nanoscale photothermal energy delivery in Pd-based catalysts. Under thermal conditions, Pd coordinated to polyoxometalates on N-doped graphene (PdPOM-CNG) exhibits higher catalytic activity than Pd directly coupled to N-doped graphene (Pd-CNG). In sharp contrast, under photothermal conditions, Pd-CNG achieves an exceptional enhancement in PET conversion from 15% to 88%, whereas PdPOM-CNG shows only a moderate increase. This reversal originates from differences in photothermal energy utilization at catalytic sites. More efficient nanoscale energy delivery increases the effective local temperature of catalytic sites and compensates for lower intrinsic catalytic activity, thereby governing photothermal catalytic behavior. These findings identify active-site photothermal energy utilization as a previously overlooked factor that determines photothermal catalytic performance.