**4.1 Water splitting**

Many attempts were taken place for the construction and engineering of setup for photocatalytic hydrogen generation [16]. Depending on the light source used (in sunlight or in a lab) reaction setup is modified, and the simplest form is described here with schematic representation **Figure 3**.

Generally, photocatalytic hydrogen production experiments were carried out in a wooden cupboard box which is known as a photocatalytic water splitting setup. This box is having the dimensions around 30 × 30 × 30 inch with closed wooden/ stainless steel chamber with observing window as shown in schematic. **Figure 3** represents the schematic of setup and can be divided into three main parts as shown in figure. Firstly, the light source fitted vertically in quartz tube having water circulation (a) arrangement for cooling purpose. 400–600 W lamp with emission wavelength 200–800 nm can be used depending upon the photocatalyst. Secondly, inside this box a two neck 250 mL borosilicate round bottom flask (b) act as a photoreactor. In photoreactor water, co-catalyst, magnetic needle and scavenger

#### **Figure 3.**

*Schematic representation of photocatalytic water splitting, (a) Light source fitted vertically in quartz tube having water circulation, (b) photoreactor, (c) a eudiometric tube.*

are added. Lastly, produced H2 in a reactor is collected in a eudiometric tube (c) for characterization on gas chromatography (GC). The eudiometer tube is with a saturated solution of sodium chloride (NaCl) to avoid the dissolution of evolved gases [16].
