Solid solutions composed of I-III-VI2 (I = Cu, Ag; III = Al, Ga, In; VI = S, Se, Te) ternary chalcopyrites and II-VI (II = Zn; VI = S, Se, Te) binary zincblendes are a group of important photocatalyst for water splitting applications. We here investigate the photocatalytic performance of CuInS2-ZnS (CIZS) nanospheres with nanoporous structures for degrading the NO poisonous gas. It is well known that the performance of a photocatalyst is determined by not only the intrinsic material properties but also the morphology of a real sample. Therefore, we first predict the fundamental material properties of CIZS for the photocatalytic application using first-principle theoretical approaches. Our results indicate that CIZS can form high crystalline structures and that its band gap and optical absorption ability are sensitively influenced by band-edge Cu-3d and In-5s electronic states. We then synthesize CIZS nanospheres with nanoporous structures, which can generate large reaction surfaces, enhance transport of photon-excited carriers, and avoid particle polymerization. It is found that the photocatalytic performance of CIZS is sensitively influenced by the mixing ratio of the constituent elements, and a high removal ratio of 47.71% is achieved by the compound with 0.04 wt% Cu. (C) 2017 Elsevier Inc. All rights reserved.