Tunable ATO-ZnO hybrid nanofluids as high-stability spectral beam splitters for efficient photovoltaic/thermal systems

Nanofluids incorporating metal nanoparticles hold considerable promise for optimizing spectral beam splitting in photovoltaic/thermal (PV/T) systems, but conventional metal based nanofluids suffer from poor stability and high cost. This study introduces highly stable ATO-ZnO hybrid nanofluids as a novel SBS for PV/T systems, resolving critical limitations of conventional metal-based nanofluids. Leveraging complementary optical properties—ZnO's exceptional ultraviolet (UV) absorption via direct bandgap transitions and ATO's strong IR harvesting through plasmonic resonance—the hybrid nanofluid exhibits enhanced optical transmittance (650–1050 nm) within the photovoltaic response band, while demonstrating strong absorption across other spectral regions. The nanofluids demonstrate outstanding long-term stability. In PV/T testing, the hybrid system sets a new benchmark with 13.59 % electrical efficiency and 57.69 % thermal efficiency, achieving a merit function of 1.692 - substantially higher than values reported for metallic nanofluid SBSs in prior studies. Performance superiority originates from quantum-enhanced UV absorption and synergistic heat localization. Synthesized via scalable aqueous processing at low material cost, this technology establishes a new paradigm for solar energy utilization through simultaneous optimization of optical efficiency, thermal stability, and economic viability.