Preparation and Photothermal Conversion of h‐BN/CuO Nanofluids

A new h‐BN/CuO nanocomposite was prepared by using boron nitride (h‐BN) and CuSO4 ⋅ 5H2O as raw materials via hydrothermal synthesis. We studied loading the CuO nanoparticles on sheet of h‐BN substrate and the stability of the h‐BN/CuO water‐based (h‐BN/CuO) nanofluids. It had both well light absorbing ability and photothermal conversion efficiency in direct absorption solar collectors (DASCs). The results show that different molar ratios of CuO to h‐BN do not affect the size of CuO nanoparticles or h‐BN substrates, but within a suitable feed ratio range, there exists an optimum feed ratio: h‐BN/CuO 0.75 : 1 which the suspension stability is the best in the base fluid. Simultaneously, supporting CuO nanoparticles on h‐BN substrate can make the absorption capacity of sunlight stronger than that of pure h‐BN. Under the simulated sunlight source, the nanocomposite with feed ratio of 0.75 : 1 was selected for the photothermal conversion test. The highest photothermal temperature of 0.05 wt % h‐BN/CuO nanofluid can reach 92.21 °C, which is 37.58 °C higher than pure water at most. Meanwhile, compared with 35.35 % for pure water, its photothermal conversion efficiency can rise to 80.18 %. In this discussion, we optimized the CuO water‐based nanofluid, which was originally have poor stability, and choosing the flake material h‐BN as the substrate to support CuO nanoparticles. The h‐BN/CuO‐n (n=1‐5) nanocomposites were synthesized by hydrothermal method. It basically solves the problem that the CuO nanoparticle is prone to agglomeration and cannot be stable existence in the water basefluid for a long time.