A relatively low surface area graphitic carbon nitride produced by a standard melamine calcination procedure was subjected to an exfoliation process and/or surface deposition of Mn-containing species. The resulting catalysts were characterized using X-ray diffraction and photoelectron spectroscopies, transmission electron microscopy, UV-vis and infrared spectroscopies, and porosimetry. The photocatalytic properties of the materials were tested in the gas-phase degradation of toluene under UV, visible and Sunlight-type illumination and their performance assessed through the measurement of the materials optical properties and subsequent calculation of the true quantum efficiency. The numerical analysis of the efficiency parameter evolution throughout the above mentioned carbon nitride samples provides quantitative estimation of the catalytic effect resulting from the exfoliation process and/or the surface deposition of Mn-containing species. Such analysis allows thus to compare the activity significance of each one of the carbon nitride modifications explored as well as the synergistic effect originated by the combined action of such modifications. (C) 2016 Elsevier B.V. All rights reserved.