Issue 39, 2020

Wavelength dependent luminescence decay kinetics in ‘quantum-confined’ g-C3N4 nanosheets exhibiting high photocatalytic efficiency upon plasmonic coupling

Abstract

Serendipitous observations offer newer insights into materials properties. Here we describe g-C3N4 nanosheets exhibiting remarkably blue-shifted photoluminescence within the 390–580 nm range centred at 425 nm which matches more closely with its ‘quantum-dots’, and yet is excitation-wavelength independent. Moreover, surprisingly, the luminescence decay becomes increasingly slow at higher emission wavelengths, by up to 10 times. The nanosheets absorb only a fraction of visible-light. To improve this, when we designed a nanocomposite of g-C3N4 and Au nanoparticles (NPs), it retained the PL characteristics and also exhibited excellent light-harvesting and photocatalytic efficiency for benzylamine (BA) oxidation. The surface plasmon resonance of the Au NPs is responsible for the high visible-light response and assisting the reaction by the ‘hot-electron’ injection mechanism, while an uncharacteristic, pronounced co-catalytic effect by them further improves the efficiency. The conversion is 98% with >99% selectivity over 1.5 h of natural sunlight and open-air, probably the highest efficiency for BA photo-oxidation reactions. Even though such a dual role by plasmonic NPs has remained unscrutinized, we argue that the charge-transfer processes for the ‘hot-carrier’ injection and co-catalytic events are well-separated in time due to a much slower photon incident frequency on a catalyst particle, enabling both to occur simultaneously in the same particle.

Graphical abstract: Wavelength dependent luminescence decay kinetics in ‘quantum-confined’ g-C3N4 nanosheets exhibiting high photocatalytic efficiency upon plasmonic coupling

Supplementary files

Article information

Article type
Paper
Submitted
14 Aug 2020
Accepted
13 Sep 2020
First published
14 Sep 2020

J. Mater. Chem. A, 2020,8, 20581-20592

Wavelength dependent luminescence decay kinetics in ‘quantum-confined’ g-C3N4 nanosheets exhibiting high photocatalytic efficiency upon plasmonic coupling

S. Mondal, L. Sahoo, Y. Vaishnav, S. Mishra, R. S. Roy, C. P. Vinod, A. K. De and U. K. Gautam, J. Mater. Chem. A, 2020, 8, 20581 DOI: 10.1039/D0TA08001B

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