A systematic comparison between graphene (GR)-semiconductor CdS and its analogs fullerene (C-60) and carbon nanotube (CNT)-semiconductor CdS composite photocatalysts for selective oxidation of alcohols has been carried out based on a reasonable benchmark framework. The results reveal that GR cannot manifest its unique advantage over its carbon allotropes in enhancing the photoactivity of semiconductor CdS. The primary roles of these carbon allotropes (C-60, CNT, and GR) are found to be quite similar in terms of structure-photoactivity correlation analysis. Overall, this work highlights that (i) the exponential increase in publications on GR-semiconductor photocatalysts has not been matched by increases in our knowledge regarding the similarity and difference of these carbon allotropes in relation to improving the photocatalytic performance of semiconductors; (ii) efforts should be more rationally focused on how to make the best use of remarkable properties of GR in designing more efficient GR-based semiconductor composite photocatalysts, thereby advancing the sufficient realization of GR's potential in constructing efficient GR-semiconductor photocatalysts for solar energy conversion. (C) 2012 Elsevier Inc. All rights reserved.