Enhancing solar energy harvesting: A comprehensive study on photothermal conversion in TiN/MXene-MOF hybrid nanofluids

• Photothermal conversion properties of TiN/NH 2 −MIL125 and MXene/NH 2 −MIL125 nanofluids were compared. • TiN/NH 2 −MIL125 hybrid nanofluid exhibited the highest light absorption. • MXene/NH 2 −MIL125 hybrid nanofluid showed the highest temperature distribution. • A photothermal conversion efficiency of 92 % was achieved using MXene/NH 2 −MIL125 nanofluid. The growing global energy demand highlights the need for renewable sources like solar energy as a key component of sustainable systems. This study focuses on developing two hybrid nanofluids, TiNML125 and MXML125, for optimizing solar energy harvesting. These nanofluids were synthesized via a solvothermal process, combining NH₂-MIL-125 with plasmonic nanoparticles, titanium nitride (TiN) and MXene (MX). Their thermal conductivity, stability, optical properties, and photothermal efficiency were analyzed. Results showed both nanofluids significantly outperformed single-component ML125, with TiNML125 improving absorption by 40 % and enhancing thermal conductivity. MXML125 demonstrated superior long-term stability, with a 25 % lower zeta potential reduction over two weeks due to MX's strong interlayer interactions. Photothermal efficiencies peaked at 60 ppm, with TiNML125 and MXML125 achieving 86 % and 96.8 %, respectively. MXML125 also showed better heat distribution and bulk temperature stability at higher concentrations. These findings highlight their potential in direct absorption solar collectors (DASCs). TiNML125 excels in thermal conductivity and absorption, while MXML125 offers superior stability and efficient heat distribution. This research bridges material innovation with practical energy solutions, advancing renewable energy technologies for a sustainable and affordable future.