Direct Z-scheme photocatalytic removal of ammonia via the narrow band gap MoS2/N-doped graphene hybrid catalyst upon near-infrared irradiation

Abstract Near-infrared (NIR) irradiation accounts for approximately 54.3% of the solar spectrum. Therefore, MoS2 and N-doped graphene (NG) were utilised to fabricate a direct Z-scheme NIR-response photocatalytic system (MoS2/NG). The photocatalytic tests showed that MoS2/NG Z-scheme photocatalytic system can result in a 99.6% degradation ratio of ammonia under NIR irradiation, whereas the removal ratio of ammonia was only 64.0% using MoS2 as the photocatalyst under similar conditions. The catalytic efficiency is still over 90.7% even if the MoS2/NG catalyst was used for five runs, indicating that it is extremely stable. The kinetic research indicated the average apparent rate constant kapp for ammonia degradation into N2 was at approximately 0.251 h−1. The enhanced photocatalytic activity of MoS2/NG was attributed to the more positive valence band level of the Z-scheme system.