Here, the authors (i) discuss the most prominent co-catalyst for H2 generation struc tured in the form of Me-TiO2/MCM-41 (Me: Ag, Co, Cu, Ni) based on structural, electronic, textural, morphological and optical characterization techniques, such as XRD, wide and small angle, XPS, Fourier-transform infrared spectroscopy, scanning electron microscopy, B.E.T., textural analysis, photoacoustic spectroscopy and photo luminescence spectroscopy; and (ii) evaluate the difference in hydrogen production in two distinct geometric reactors based on a theoretical study of light distribution inside the reactors supported by the experimental quantum yield calculation. As a result, copper-doped photocatalyst generated higher hydrogen amount compared to the others. The high photocatalyst performance was due to the greater lamp spec trum absorption, marked by the low bandgap value, and high photoactivity justified by the low rate of electronic recombination. The hydrogen generation in the quartz reactor was seven times higher than the annular one, and when at maximum light power, it is comparable to the most sophisticated reaction systems found in litera ture. The larger light exposure area per unit volume of the quartz reactor compared to the annular one is the reason why it obtained better results due to the lower emit ted photon blockade, with a 1.81% apparent quantum yield
