Enhanced Hydrogen Generation Performances and Mechanism of Al-Water Reaction Catalyzed by Flower-Like Biocl@Cnts

Abstract

In this work, flower-like BiOCl@CNTs composites with high activity are introduced into Al by ball milling (Al-BiOCl@CNTs powder ) or ball milling combining spark plasma sintering (SPS) (Al-BiOCl@CNTs block ) to improve hydrogen generation performance of the Al-water reaction. The results indicate that BiOCl@CNTs can significantly promote the performance of hydrogen generation from Al-water reactions. Moreover, Al-BiOCl@CNTs block by sintering is obtained, and its performance of hydrogen generation is further improved. The Al-BiOCl@CNTs block has achieved hydrogen release at room temperature, and hydrogen yield and conversion yield of the Al-7 wt% BiOCl@CNTs reach 1172.9 mL·g -1 and 92.7% at room temperature, respectively, which are better than that of Al-7 wt% BiOCl@CNTs powder (864.9 mL·g -1 and 68.4%). The Al-BiOCl@CNTs block has better oxidation resistance, with a hydrogen yield of 864.9 mL·g -1 even after 35 days under air. The XRD analysis illustrates that BiOCl@CNTs significantly improve the performance of the Al-water reaction, owing to the in situ formation of Bi and Bi 2 O 3 . Density functional theory (DFT) calculates results indicate the existence of Bi and Bi 2 O 3 in situ both can improve the adsorption capacity of Al to water, but the Bi accelerates the breaking of O-H bonds in water, thereby promoting the release of hydrogen from the Al-water reaction.

Keywords: Hydrogen generation, Al-BiOCl@CNTs, DFT calculations