Enhancement of selectivity towards the synthesis of hydrogen peroxide by dimensional effect in mesoporous carbon

Efficient and selective electrocatalysts materials are currently needed for renewable energy conversion. This work studies the influence of internal channel modifications and the type of mesoporous silica that changes the electrocatalytic activities from the synthesized mesoporous carbon. Thus, MCM-41 and SBA-15 functionalized with amine (A) or diamine (D) groups and polyaniline (PANI) after pyrolysis produces derived mesoporous heteroatom-doped carbon that were evaluated as electrocatalyst in oxygen reduction reaction (ORR) for fuel cell systems. ORR can produce two types of products, allowing us to differentiate the main electrocatalytic activities of the synthesized mesoporous carbons. Therefore, the electrocatalytic results correlated the number of electrons transferred with the kind of ORR product generated. CS41/D/PANI, mesoporous carbon obtained from MCM-41 modified with diamine groups, was selective towards the production of H 2 O 2 with 2.6 electrons transferred during the reaction while the CS41/A/PANI, mesoporous carbon obtained from MCM-41 modified with amine groups, presented high catalytic activity compared to Pt/C, leading to complete reduction of O 2 to H 2 O. However, SBA-15 does not generate mesoporous carbons with selectivity for ORR. Then, this result is directly correlated with the influence that the mesoporous carbon suffered by the silica pore size and initial modification with amine or diamine groups. Finally, the chronoamperometry analysis demonstrated carbon materials with stability over a long period and high methanol tolerance compared with noble metals like Pt/C catalysts. • Distinct mesoporous silicas produced mesoporous carbon from polyaniline with selectivity to electrocatalysis of oxygen reduction reaction. • SBA15 and MCM41 were used as a template and the mesoporous carbon from polyaniline and MCM41 presented interesting selectivity of the oxygen reduction reaction. • The pore size change of mesoporous silica used as a template influence directly the electrocatalysis properties of mesoporous carbon obtained.