3.2.1. XRD Analysis

Figure 3 shows the XRD patterns of the synthesized alloys containing various Zn content. It can be seen that all samples mainly consist of two phases: crystalline Al phase (JCPDS file #04-0787) and In3Sn intermetallic compound (JCPDS file #07-0345). Besides, Ga-related diffraction peaks have not be observed. Similar phenomenon is common in previous studies of Al-Ga-based alloys, and it has been confirmed that Ga exists as a form of Al (Ga) solid solution [30–32]. Yet, due to a low doping amount of Ga in the raw materials and the close atomic radius of the two atoms, the positions of Al diffraction peaks have not changed significantly. Additionally, no significant characteristic peaks of crystalline Zn phase were found, which maybe owing to the low doping amount or similar properties of Zn and Ga in Al (i.e., high solid solubility, similar atomic radius). Thus, the existence of Zn needs to be further confirmed by EDX and other analysis.

**Figure 2.** *Cont*.

**Figure 2.** Hydrogen generation rates of the Al-Ga-In3Sn-Zn alloys at temperatures of (**a**) 40 ◦C, (**b**) 50 ◦C, (**c**) 60 ◦C.

**Figure 3.** XRD patterns of the remnant alloys.
