The photocatalytic activity of transition metal dichalcogenides (TMDCs) can be improved by loading them on carbon materials, which can reduce the recombination of photogenerated electrons and holes. However, the already existing approaches to producing carbon TMDC nanocomposites have been complicated and time-consuming, and have involved the use of organic solvents or sometimes of dangerous chemicals. Here, we report a one-step strategy for the large-scale in situ synthesis of C fibers@MX2 (M = W or Mo; X = S or Se) nanoplates core shell composites simply by heating mixtures of cheap polyacrylonitrile fibers and metal oxides in S or Se vapor. The photocatalytic performance of the as synthesized composites was evaluated by the degradation of methylene blue, rhodamine B, Cr(VI), and E. coli. Surprisingly, such composites exhibited greatly improved photocatalytic activity and excellent stability under full-spectrum light irradiation. This strategy is a general, low-cost, and environmentally friendly solution for the synthesis of highly efficient semiconductor photocatalysts for industrial applications. (C) 2017 Elsevier Inc. All rights reserved.