Cu-Ag bimetallic nano-catalyst anchored on polyvinyl alcohol sponge for catalytic reduction of 4-nitrophenol

With increasing interest and demand for treating organic wastewater, fabricating a heterogeneous catalyst combining low-cost, excellent catalytic efficiency, and good recyclability is necessary but remains challenging. In this work, we developed a kind of low-cost Cu-Ag bimetallic nano-catalyst anchored on polyvinyl alcohol sponge (Cu-Ag/PVA) via step impregnation and reduction method, which demonstrated excellent catalytic efficiency and good recyclability for the reduction of the organic pollutant 4-nitrophenol (4-NP). The compositional and microstructural results confirmed that Cu-Ag bimetallic nanoparticles with an average size of tens of nanometers were uniformly anchored on the porous PVA sponge. The catalytic results showed that the prepared Cu-Ag/PVA exhibited an appealing catalytic performance and recyclability compared with monometallic Cu or Ag nano-catalyst, which is ascribed to the reason that bimetallic Cu-Ag has lower binding energy and is easier to transfer electrons in the catalytic reduction of 4-NP compared to monometallic catalyst. The optimal kinetic catalytic rate constants for Cu-Ag/PVA is 0.54 min−1, and the conversion of 4-NP maintained above 98% after twelve consecutive catalytic cycles. Therefore, this inexpensive, efficient, and recyclable Cu-Ag/PVA catalyst has potential application in organic wastewater treatment.