A multifunctional upconversion-quantum dot photocatalytic platform for near-infrared-driven environmental remediation and complex organic synthesis

Abstract

Near-infrared (NIR) Energy Transfer Upconversion (ETU) overcomes the photon energy limitations of single-photon processes via nonlinear optical effects, demonstrating unique advantages in deep material penetration and multi-electron transfer. A multifunctional photocatalytic platform that harnesses low-energy NIR for both environmental remediation and complex, multi-step organic synthesis is reported. For the first time, a single ternary nanostructure, NaYF₄, Yb : Tm/Co₃O₄/g-C₃N₄ nanosheets, is demonstrated to bridge these disparate chemical domains. The system operates via a sophisticated ETU-FRET (Förster Resonance Energy Transfer) energy relay, where Yb³⁺ sensitizers absorb 980 nm photons and the energy is subsequently upgraded via a multi-photon ETU process involving Tm³⁺ activators, a nonlinear mechanism confirmed by power-dependent emission studies (slopes ≈ 2). The resulting high-energy excitons are then efficiently channeled to the Co₃O₄/g-C₃N₄ nanosheets heterojunction via FRET, converting inert NIR light into potent redox power. The platform's versatility is showcased by its ability to drive both the rapid degradation of pollutants and, more impressively, a one-pot cascade synthesis of medicinally important benzazole scaffolds. Culminating in this work, the protocol was successfully applied to the gram-scale synthesis of the commercial drug, thiabendazole. This work pioneers a general strategy for converting sub-bandgap photons into high chemical potential, establishing a versatile NIR-driven platform for sustainable chemistry.