Decomposition of H2O2 on activated carbon obtained from olive stones

Catalytic performance of carbon nanotubes in H2O2 decomposition: Experimental and quantum chemical study

“…4a) in parallel with the decreasing surface density of protonated sites (Fig. 4b) [29].The same correlation for O-CNT samples was observed until pH=7.0.…”

“…With increasing pH the decomposition of H 2 O 2 improved on both samples. Obviously, this tendency is connected on the one hand with the enhanced dissociation of H 2 O 2 as a weak acid [29] and on the other hand with the changes in the charge state of the functionalized carbon surface. Figure 4b demonstrates that a relatively large proton excess accumulates on the N-CNT in acidic media due to the negative charge of the basal plane and the protonation reaction of its decorating basic sites (amino groups and quaternary nitrogen atoms as also considered in our quantum-chemical calculations), e.g., CNT-NH 2 It is observed that activity of the N-CNT decreases until the third cycle, a feature that may be associated with slow deactivation of the N-functionality in the carbon system.…”

“…Oxidation under mild conditions (e.g., 15% H 2 O 2 , 100ºC, 3 hrs [27]) leads to shortened and uncapped CNTs with carboxylic groups on their surface. Nevertheless, it is well known that HPD is one of the oldest reactions found to be catalyzed by carbon materials, especially by activated carbons [28,29]. Earlier, it was found that CNT, compared to graphene and activated carbon, is also able to catalyze HPD [30].…”

“…Decomposition of hydrogen peroxide over a solid surface is a complex homolytic chain process [29,34,35]. The limiting step of this reaction is the disintegration of H 2 O 2 molecule into two HO • radicals through a radical mechanism.…”

“…The limiting step of this reaction is the disintegration of H 2 O 2 molecule into two HO • radicals through a radical mechanism. On the other hand, ionic decomposition may also occur as H 2 O 2 is a weak acid (H 2 O 2  H + + OOH -, pKa = 11.6) [29]. Both processes are influenced by pH, the presence of catalytic ions (e.g., Fe 3+ , I -) and also by the chemistry of the solid surface, e.g., the carbon material [29].…”