“…As described earlier, the electrochemical storage is facilitated by the redox reactions at the electrode materials; hence, the morphology and catalytic properties are of utmost importance for efficient electrochemical storage [160] . Previously materials for the electrochemical storage of hydrogen were synthesised using different methods, including thermal decomposition [150] , [152] , [155] , [156] , [157] , [158] , [159] , [160] , ultrasonic synthesis [167] , combustion [159] , [160] and chemical precipitation [162] , [163] , [164] , [165] , [166] , [167] , [168] . Maryam et al [167] demonstrated an ultrasound facilitated synthesis of CdSnO 3 -graphene nanocomposites for the electrochemical storage of hydrogen.…”