The gold nanoclusters, added in low percentage to a semiconductor nanomaterial, will induce plasmon resonance effect that enhances the visible light harvesting. In photocatalysis application, it is beneficial to have a semiconductor that absorbs in both UV and visible light. So, adding gold nanocluster (in condition to adjust the percentage added), is able to enhance the semiconductor efficiency and by that the photocatalysis quantum yield (calculated from the consumed concentration under irradiation).
Wang, S., Meng, X., Das, A., Li, T., Song, Y., Cao, T., Zhu, X., Zhu, M. and Jin, R., 2014. A 200‐fold quantum yield boost in the photoluminescence of silver‐doped AgxAu25− x nanoclusters: the 13 th silver atom matters. Angewandte Chemie International Edition, 53(9), pp.2376-2380.