The design of a polyaniline-decorated three dimensional W18O49 composite for full solar spectrum light driven photocatalytic removal of aqueous nitrite with high N2 selectivity

Photocatalysis using solar energy is the most promising green technology for nitrite removal. However, effective photocatalytic performance is often challenged by the limited light absorption, utilization of expensive noble metals and undesired products (nitrate and ammonium). Here, we report for the first time that a full solar light response polyaniline-decorated three dimensional W18O49 composite (PANI@W18O49), a noble metal-free photocatalyst, possesses excellent photocatalytic activity for aqueous nitrite removal with high N-2 selectivity. The prepared sample was thoroughly identified via XRD, Raman, FTIR, SEM, TEM, UV-vis DRS and PL. The catalytic results demonstrated that over 80% N-2 selectivity (initial concentration 1.0 mM) was achieved through the PANI@W18O49 without sacrificial agent under 300 W Xe lamp irradiation for 60 min. Such advantages were attributed to the built-in junction between n-type W18O49 and p-type PANI, offering suitable redox levels of electron-hole pairs for NO2- reaction. The modification of PANI also benefited the light harvesting ability and activated carriers migration, the calculated rate constant of PANI@W18O49 is about four times as high as that of W18O49. The current study not only prepared a promising photocatalyst, but also provides new insights into improving the photocatalytic activity and N-2 selectivity for nitrite treatment. (C) 2018 Elsevier B.V. All rights reserved.