Controlled photocatalytic hydrolysis of nitriles to amides by mesoporous MnO2 nanoparticles fabricated by mixed surfactant mediated approach

•Synthesis of mesoporous MnO2 by using mixture of cationic and anionic surfactants with variable pore volume.•The cat-anionic surfactant yields 5 times higher surface area (195.32 m2/g) than their corresponding individual form (CTAB 29 m2/g and SDS 36 m2/g).•Synergic effect, low critical aggregation concentration of cat-anionic surfactant is endorsed for its high surface area.•The mesoporous MnO2 as a novel catalyst for the hydrolysis of nitriles to amides.•Higher yield (90%) in basic reaction medium compare to neutral medium (70%).

The solid-phase MnO2 nanoparticles fabricated by surfactant template method were exploited as the photocatalyst for the effective one-step synthesis of amides. Cationic or anionic surfactants and their combinations were used as porous templates to obtain the mesoporous MnO2 nanoparticles with variable pore volume (0.23-1.95 cm3/g). The morphological and structural observation of the material confirms the uniform facet structure (37.68 nm) of MnO2 nanoparticles. The surface elemental state was confirmed by XPS analysis confirming Mn 2p3/2 (642.5 eV) and Mn2p1/2 (654.7 eV) spin states, that are common for the tetravalent Mn ions. Presence of surfactant as stabilizer was also witnessed with a strong peak of C 1s (283-286 eV). The textural parameters obtained from XRD and Raman analysis depicted the β-phase and rutile type framework of MnO2. The selective conversion of nitriles to amides was studied without any acid by products under visible light irradiation in the basic/neutral medium. Amides were obtained from various substrates (nitriles) with excellent yields (70-90%).

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