Titania and zirconia are both known for their chemical stability and photocatalytic properties. The wide band gap of these two types of catalysts (TiO2: ~3.2 eV; ZrO2: >5 eV) resulted in limited photocatalytic activity under visible light. As previously mentioned, hydrogen production from water splitting catalyzed by photocatalysts has become attractive in the past few decades. ZnS, ZnCdS, MoS2, and their composite materials have been studied for the photocatalytic hydrogen production.