Branched CuxAuy nanoalloy with controllable atomic ratios and "clean surface": Synthesis and their superior performances in hydrogen evolution reaction and biosensors

Narrow detection range and restricted durability of electrocatalysis are the two challenges for biosensors and hydrogen generation. This work provided a one-pot synthesis of branched CuxAuy nano-alloy with controllable atomic ratio and “clean surface” by a mild co-reduction. Different from conventional method that applied an elevated temperature or pressure, the atomic ratio of CuxAuy alloy was tailored by controlling kinetics parameters. And the no surfactant process resulted in a "clean surface". The “clean surface” coupled with an optimal atomic ratio enabled Cu38Au62 alloy a superior biosensor performance. As applied in nitrite detection, the sensor by surface cleaned Cu38Au62 alloy could achieve the wide detection range up to 125.0 mM. On the contrary, sensor performance for the CuAu alloy by surfactant-assisted was negligible. It is suggested that an optimal atomic ratio for CuxAuy would not only rationalize the cost but also be beneficial to their biosensor performance. In the glucose detection, sensitivity for sensor by Cu38Au62 alloy is 718.43 µA/mM·cm2 from 0 to 150 mM (by linear sweep voltammetry), which is much superior to that by other CuxAuy nano-alloy. The constructed glucose sensor was further applied to detect sugar content for coca-cola. The synergistic effect of Cu and Au atoms could also accelerate the H2 deprivation. And the volcano plots for overpotential by CuxAuy alloy were also summarized. In the hydrogen evolution reaction (HER) process, it is verified that the reconstruction of CuxAuy alloy surface would not only overcome the activity degradation but bring out a reduced overpotential.