Bimetallic Ni-Co nanoparticles confined within nitrogen defective carbon nitride nanotubes for enhanced photocatalytic hydrogen production.

This work for the first time reports bimetallic Ni-Co and monometallic (Ni and Co) nanoparticles (NPs)-engineered carbon nitride nanotubes with nitrogen vacancies (V-CNNTs) for visible-light photocatalytic H2 generation application. The bimetallic Ni-Co NPs have an average size of less than 5 nm and are homogenously dispersed along the nanochannels of V-CNNTs. The composition of the bimetallic NPs plays an essential role to maximize photocatalytic activity. With the optimal Ni/Co atom ratio of 3:1, Ni-Co/V-CNNTs nanohybrids yielded a H2 production rate of 4.19 µmol/h, which is higher than those of monometallic counterparts and V-CNNTs. The intimately loaded Ni-Co NPs and incorporated nitrogen vacancies enhance the photocatalytic performance through extended light absorption, abundant active sites, strong metal-support interaction, and efficient charge carrier transfer along the axial direction. This study presents a stable and highly efficient hybrid as a promising photocatalyst for visible light photocatalytic H2 production through water splitting.