In-situ graphene modified self-supported boron-doped diamond electrode for Pb(II) electrochemical detection in seawater

[Display omitted] •A bilayer graphene was facilely in-situ grown on SBDD through copper catalyzing.•The graphene recognition showed superior homogeneity and low defect content.•G/SBDD showed a sensitivity of 0.475 μA L μg−1 cm−2 in the range of 1–100 ppb.•G/SBDD exhibited good stability with a signal retention of 96% after 60 days. This work focuses on improving the repeatability and lifetime of a sensor for the electrochemical detection of trace Pb2+ in seawater. An in-situ graphene modification method was proposed to prepare graphene functionalized self-supported boron-doped diamond (G/SBDD) electrode. A pre-coated copper film on SBDD catalyzed graphene growth through vacuum-annealing at the temperature of 1000 °C. The formation of in-situ graphene was systemically investigated, and a homogeneous bilayer graphene with low defect was in-situ grown on SBDD. Then, the electrochemical behavior of SBDD and G/SBDD for Pb2+ was evaluated in simulated seawater. Compared to SBDD, G/SBDD exhibited a larger active surface area of 0.27 cm2, a higher response signal, and a smaller charge transfer resistance (Rct) of 312 Ω cm−2. Under optimized experimental conditions (a deposition potential of −0.6 V and an accumulation time of 125 s), the G/SBDD electrode achieved a sensitivity of 0.475 μA L μg−1 cm−2 and a detection limit of 0.21 μg L−1 over a wide linear range of 1–100 ppb. Also, the electrode exhibited good reproducibility (RSD value of 2.7%), enhanced stability (96% of the initial response signal after 60 days) and high selectivity. The performance of the designed electrode holds promise for monitoring Pb2+ in seawater.