NO3− removal with a new delafossite CuCrO2 photocatalyst

The removal of NO3− by a CuCrO2-mediated catalytic photoprocess was investigated under mild conditions. The delafossite CuCrO2 exhibits an excellent chemical stability over the whole pH range and relatively a large specific surface area when elaborated by chemical means. The optical gap was found to be 1.28 eV, close to the optimal value required for terrestrial applications. The conduction band is located at −1.06 VSCE and thus lies below the NO3− level leading to a thermodynamically favorable nitrate reduction under visible light. The possibility of identifying the reaction products via the intensity-potential characteristics was explored. The reaction of NO3− proceeds in competition with the water reduction and seems to be the major reason in the regression of the photoactivity during prolonged testing. The complete conversion occurs in less than ~4 h with a quantum efficiency of ~2%.