“…In the literature, a few researchers have reported the reduction of pNP over metal-free catalysts such as graphene and MOFs-based catalysts [ 12 , 16 ]. However, metal [ 17 , 18 , 19 , 20 , 21 , 22 ] and metal oxide [ 21 , 22 , 23 , 24 , 25 ] nanoparticles and nanocomposites have widely been applied, due to their excellent efficiency in lowering the reduction potential value [ 26 , 27 , 28 ]. Furthermore, their adaptable morphological, structural, chemical, physical, and optical properties have contributed to utilizing them in a wide area of research, including sensing, imaging, electronics, adsorption, and heterogeneous catalysis [ 15 ].…”