A High-Performance Cr 2 O 3 /CaCO 3 Nanocomposite Catalyst for Rapid Hydrogen Generation from NaBH 4 .

This study aims to prepare new nanocomposites consisting of Cr 2 O 3 /CaCO 3 as a catalyst for improved hydrogen production from NaBH 4 methanolysis. The new nanocomposite possesses nanoparticles with the compositional formula Cr 2-x Ca x O 3 (x = 0, 0.3, and 0.6). These samples were prepared using the sol-gel method, which comprises gelatin fuel. The structure of the new composites was studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, environmental scanning electron microscopy (ESEM), and X-ray spectroscopy (XPS). The XRD data showed the rhombohedral crystallinity of the studied samples, and the average crystal size was 25 nm. The FTIR measurements represented the absorption bands of Cr 2 O 3 and CaO. The ESEM micrographs of the Cr 2 O 3 showed the spherical shape of the Cr 2 O 3 nanoparticles. The XPS measurements proved the desired oxidation states of the Cr 2-x Ca x O 3 nanoparticles. The optical band gap of Cr 2 O 3 is 3.0 eV, and calcium doping causes a reduction to 2.5 and 1.3 eV at 15.0 and 30.0% doping ratios. The methanolysis of NaBH 4 involved accelerated H 2 production when using Cr 2-x Ca x O 3 as a catalyst. Furthermore, the Cr 1.7 Ca 0.3 O 3 catalyst had the highest hydrogen generation rate, with a value of 12,750 mL/g/min.