Abstract

Concentrating solar power (CSP) needs efficient thermal storage, but standard molten "solar salt" is limited by modest heat capacity and high-temperature stability. We assess hexagonal boron nitride (h-BN) nanosheets as additives to enhance solar salt. Nanofluids with 0.5-3 wt.% h-BN are prepared via scalable dry mixing. Thermogravimetric analysis and differential scanning calorimetry quantify decomposition temperature, melting, and heat capacity; XRD, SEM, and Raman probe structure and morphology before and after heating. Low loadings (0.5%-1%) give the best results: heat capacity increases by similar to 15% +/- 3% and decomposition temperature by similar to 5% versus neat salt, while chemical and phase stability are maintained. At higher loadings (2%-3%), h-BN agglomeration reduces benefits and degrades morphology. These trends are consistent with-though not proof of-interfacial nanolayers and ionic structuring at well-dispersed 2D surfaces that redistribute heat. Scope is intentionally limited: thermal conductivity, viscosity, and multicycle durability were not measured and remain for future work. Overall, we outline a processing-structure-property window that maximizes heat capacity at low additive levels, positioning h-BN as a stable, inert, and scalable additive for next-generation CSP storage.