Humidity induced deactivation of Al2O3 and SiO2 supported Pd, Pt, Pd-Pt catalysts in H2 + O2 recombination reaction: The catalytic, microcalorimetric and DFT studies

•Hydrogen and oxygen reaction on Al2O3 and SiO2 supported Pd, Pt and Pd-Pt.•Activity and deactivation studied by catalytic and microcalorimetric methods.•Pt and Pt-rich Pd-Pt catalysts much more deactivated by humidity than Pd.•Stronger interaction of water–Pt compared to Pd (DFT calculation).