We report a novel passive microfluidic mixer design for mixing enhancement based on dynamic disturbances due to bubble generation produced by catalytic decomposition of hydrogen peroxide. A Y-shaped passive microfluidic mixer with a width and depth of 1 mm and 50 µm, respectively, with platinum deposition on the partial undersurface of the mixing channel for H2O2 catalytic decomposition, is demonstrated. Various Reynolds numbers (0.06 to 63.5) and H2O2 concentrations are tested to investigate their effects on the mixing. The experimental results show that mixing can be significantly improved either with the decrease of volumetric flow rate at a given H2O2 concentration or with the increase of H2O2 concentration at intermediate Reynolds numbers based on the present design. The mixing index scatters between 0.8 and 1.0 at x ≥ 15 mm for all H2O2 concentrations if Re=0.06 in the mixing channel. However, the H2O2 concentration has no significant effect on mixing provided Re ≥ 63.5. In addition, the maximum mixing enhancement for QL=1, 10, 100, and 1000 µL/min (Re=0.06, 0.63, 6.35, and 63.5) at x ≥ 15 mm are 5.7, 11.85, 6.27, and 4.8, respectively, with 0.1 M<[H2O2]<8.8 M in this study.