A theoretical model of MHD mixed convective Cu-water nanofluid boundary layer flow over flat vertical plate has been developed and investigated. As a novelty, firstly, modified Buongiorno's model is utilized to include the effects of Brownian motion, thermophoresis and volume fraction for nanofluid. Secondly, thermal energy equation and concentration equation are modeled with the help of Cattaneo-Christov theory of heat and mass flux, respectively. Due to this non-Fourier's and non-Fick's approach, two parameters namely, thermal relaxation parameter and solutal relaxation parameter were introduced in thermal energy equation and concentration equation, respectively. In addition, the surface of flat plate is subjected to suction, convective heating and zero wall mass flux condition. Authors have used the similarity method and through analysis it is shown that transport equations can be converted to ODEs with the help of suitable similarity transformations. The analysis and computed results shows that various dimensional and non-dimensional parameters influence the velocity, temperature and concentration profiles. The pattern and behavior of boundary layer is depicted graphically. The results for skin friction coefficient and heat transfer coefficient are outlined in tabular form. The result of passive control of nanoparticles at the surface is that Brownian motion parameter does not influence the temperature profiles of nanofluid flow and heat transfer rate at the surface. Heat transfer coefficient is positively correlated to thermal relaxation parameter and Biot number, whereas thermophoresis parameter causes it to decrease. The flow of nanofluid is aided by buoyancy ratio parameter and thermophoresis parameter but B Sawan Kumar Rawat