“…The absorption peaks located at 3223 cm −1 , 1770 cm −1 , 1463 cm −1 , 1198 cm −1 , and 455 cm −1 were assigned to –OH, CO, –CH 2 , B–O and Ga–O, groups, respectively, and are in agreement with the aforementioned XPS results. 43–49 The absorption peak of CO bonds at 1770 cm −1 is assigned to the vibration of CO bonds in –COOR functional groups. The absorption peak of the –OH group at 3223 cm −1 originates from adsorbed water.…”