▎ 摘　　要

A boron-doped graphene (BG)/boron-doped diamond (BDD) composite film was obtained by continuously growing BDD and BG by chemical vapor deposition. In this process, the sp(3) C-C bonds in the diamond phase structure are directly converted into sp(2) C-C bonds in graphene to combine the two carbon materials, while BG nanosheets are vertically grown on the exposed planes of BDD crystals. These process features impart the vertical BG (VBG)/BDD film a large specific surface area and high electrocatalytic activity, resulting in an electroactive surface area of 2.35 cm(2). Electrodeposition can be used to load a large number of Au nanoparticles (NPs) on the VBG/BDD electrode. The Au-VBG/BDD electrode was used to construct an immunosensor capable of simultaneously quantifying carcinoembryonic antigen (CEA) and carcinoma antigen 125 (CA 125) at concentrations of 0.5-100 pg mL(-1) and 0.5-100 mU mL(-1), respectively, with corresponding detection limits of 0.15 pg mL -1 and 0.09 mU mL(-1). This method is suitable for the practical detection of CEA, CA125, and other tumor markers in human body fluids, allowing early cancer diagnostics and timely treatment.