Beyond Photoelectrochemical Water Splitting

Photoelectrochemical (PEC) water splitting area has been investigated for decades as a means to convert sunlight to fuels. To date, PEC still faces many challenges, ranging from low efficiency, poor stability and noncompetitive cost. I will present two examples of our recent efforts in overcoming some of the challenges facing PEC. The first examples is related to the well-known hydrogen evolution reaction (HER) catalyst, MoS2. For MoS2, the perfect basal plane is long regarded as inert, but it can be activated for HER by creating S-vacancies. The activity of the S-vacancy can also be further improved by either strain or transition metal doping. The second example is switched to the water oxidation side of water splitting. So far, most researches on water oxidation has been focusing on producing O2. Here, I will discuss the potential of using the competing two-electron water oxidation pathway to produce a valuable chemical, i.e., H2O2. Importantly, such a reaction can be coupled with oxygen reduction to H2O2 reaction to construct an unassisted PEC system, which uses light, water and oxygen to simultaneously produce electricity and H2O2:

Light + 2H2O + O2 = Electricity + 2H2O2

Speaker: Ziaolin Zheng, Stanford