Hydrogen absorption abilities of oxide semiconductors

In this study, hydrogen sensing/storage ability of pure and boron dopped CoGa2O4 nanoparticles are provided. Reflux sol-gel method was used on CoGa2O4 synthesise for the first time. Annealing temperature was decided based on the gel compound of CoGa2O4 reaction in DT-TGA measurement. Based on thermal analysis result, pure CoGa2O4 was annealed at 300°C, 600°C, 900°C, and 1200°C. Crystal structure of powders with different annealing temperatures were characterised in XRD and XPS. XRD pattern was compared with PDF#00-011-0698 of COD database. The result of diffraction pattern was illustrated spinel form of CoGa2O4 with no external peaks. Same procedure of particle synthesis was applied to the %10, %20, and %40 B doped CoGa2O4 powders. XRD patterns were further used in Rietveld refinement. The results were revealed that the B content in CoGa2O4 fills octahedral sites first. Afterwards, B elements settle in the position of tetrahedral sites. Crystal size parameter of pure CoGa2O4 was found 8.3259±0.0001Å. Addition of B was increased crystal size parameter. Obtained crystal parameter size for %10, %20, and %40 B doped CoGa2O4 are 8.3281±0.0001Å, 8.3289±0.0001Å, and 8.3279±0.0001Å, respectively. As a result of refinement, B addition was firstly saturated in Ga+3 sites, then started to occupy Co+2 positions. Contribution of B content in tetrahedral sites was decreased unit cell. Synthesised pure and undoped CoGa2O4 powders were prepared as target for RF magnetron sputtering. Targets were mounted in chamber and deposited onto quartz substrates. Optical band gap properties of thin films were understood by Uv-Vis spectrometer results. Thin films were tested for hydrogen storage and sensing ability in homemade vacuum measurement system. Pure and B doped CoGa2O4 films were tested for H2, CH4, O2, and Ar gas sensing ability. The highest result was observed with 4.4% for H2 sensing ability.