Fabrication and characterization of TiO2 deposited black electroless Ni-P solar absorber

Abstract

Abstract Preparing a selective, efficient, and low-cost solar absorber is one of the main challenges in solar to thermal energy conversion. In this paper, black electroless Ni P (ENi-P) solar absorber has been fabricated, and the effect of nanoporous TiO2 antireflection layer (ARL) on its optical and corrosion properties has been investigated. The optimum black coating was obtained by blackening in 9\u202fM nitric acid solution at 50\u202f°C for 40\u202fs, in which a solar absorptance of 99.3% was achieved. Deposition of TiO2 ARL increased the solar absorptance of coating to 99.7% and addition of 0.8\u202fg Pluronic F127 (F127) as pore former, further increased this value to 99.9% and solar-to-heat efficiency of the coating from 78.1 to 78.7%. F127 added coatings exhibited elongated and irregularly shaped pores with dimensions of a few tens of nanometers. Also, deposition of TiO2 ARL decreased the corrosion current density (icorr) of black ENi-P coating in 3.5\u202fwt% NaCl solution from 20 to 4\u202fμA/cm2. The results of this work indicate that the TiO2 deposited black ENi-P coating can be a suitable choice for black coating applications.