Aiming to improve the electron transfer efficiency between redox protein/enzyme and electrode, Pt-3D graphene oxide aerogel (3DGA) nanocomposite was synthesized via a facile one-step hydrothermal method and used as a new biocompatible carrier for protein/enzyme. The morphology and structure of Pt-3DGA nanocomposite were characterized by SEM, TEM, XPS, XRD, Raman and BET. Then a new modified electrode was fabricated with Pt-3DGA-horseradish peroxidase (HRP) biocomposite suspension and Nafion solution coated on carbon ionic liquid electrode (CILE). The performances of Nafion/Pt-3DGA-HRP/CILE were further checked by various methods with the well-maintained 3D structure, good retention of bioactivity of HRP and the enhanced electrochemical ability. Direct electrochemistry of HRP was investigated with a pair of well-shaped redox peaks appeared with the peak-to-peak separation as 78 mV. Electrochemical parameters including electron transfer coefficient (alpha) and heterogeneous electrode reaction rate constant (k(s)) are calculated to be 0.52 and 3.35 s(-1), respectively. Nafion/Pt-3DGA-HRP/CILE shows outstanding electrocatalytic activity towards trichloroacetic acid (TCA) reduction with a wide detection range of 0.5 similar to 42.0 mmol/L. Nafion/Pt-3DGA-HRP/CILE can be successfully utilized for the analysis of TCA contents in real samples with good recovery. (C) 2018 The Electrochemical Society.