After 30 min of the reaction, the H2 generation reaches saturation (Figures ) and the color of the water changes from transparent to blackish brown (Inset of Figure and Figure ). The reacted particles separated from the water after reaction saturation was found in the nanoscale range (a few nanometers) under microscopic analyses (Figure ). Thus, nanostructuring of GdTe is possible by the simple addition of water without any external energy and the GdTe surface morphology changes with time and forms black-colored nanoparticles in water (Figure ). This surface reaction is shown by in-situ optical microcopy (Figure and GdTe crystal along with the formation of Gd-Ox. The de-convoluted O 1s spectrum shows two peaks positioned at 530.2 eV and 531.6 eV, which could be ascribed to oxygen-metal bonds and surface adsorbed oxygen, respectively. The core level spectra of Gd 3d reveal its characteristics peaks at 1186.5 and 1218.6 eV by virtue of 3d5/2, and 3d3/2, respectively which originates due to the spin-orbital coupling on a doublet. Absorption spectra also confirms the regeneration of GdTe after reaction and melting (Figure ). Therefore, due to the presence of GdTe in GT-II sample, it regained its ability to produce H2 when reacted with water at equivalent rate. Although the amount of generated H2 decreases from freshly prepared GdTe, Further, The Te 3e XPS profile can be assigned to Te 0 (572.9 eV), O-Te3d3/2 (575.9 eV), C-Te3d5/2 (583.3 eV), and O-Te3d5/2 (586.2 eV) peaks (Figure ), indicating the formation of elemental Te and oxides of Te along with Gd2O3 and Gd2Te3 .