Fabrication of an electrochemical sensor for hydrogen peroxide (H 2 O 2 ) detection was demonstrated. H 2 O 2 is a major messenger molecule in various redox-dependent cellular signaling transductions. Therefore, sensitive detection of H 2 O 2 is greatly important in health inspection and environmental protection. Carbon nanowalls (CNWs) are composed of few-layer graphenes standing almost vertically on a substrate forming a three-dimensional structure. In this work, CNWs were used as a platform for H 2 O 2 sensing, which is based on the large surface area of conducting carbon and surface decoration with platinum (Pt) nanoparticles (NPs). CNWs were grown on carbon fiber paper (CFP) by inductively coupled plasma-enhanced chemical vapor deposition to increase the surface area. Then, the CNW surface was decorated with Pt-NPs by the reduction of H 2 PtCl 6 . Cyclic voltammetry results indicate that the Pt-decorated CNW/CFP electrode possesses excellent electrocatalytic activity for the reduction of H 2 O 2 . Amperometric responses indicate the high-sensitivity detection capability of the Pt-decorated CNW/CFP electrode for H 2 O 2 .

Hydrogen peroxide (H 2 O 2 ) reactions on platinum nanoparticle-decorated carbon nanowalls (Pt-CNWs) under potential applications were investigated on a platform of CNWs grown on carbon fiber paper (CFP) using plasma-enhanced chemical vapor deposition. Through repeated cyclic voltammetry (CV), measurements of 1000 cycles using the Pt-CNW electrodes in phosphate-buffered saline (PBS) solution with 240 µM of H 2 O 2 , the observed response peak currents of H 2 O 2 reduction decreased with the number of cycles, which is attributed to decomposition of H 2 O 2 . After CV measurements for a total of 3000 cycles, the density and height of CNWs were reduced and their surface morphology changed. Energy-dispersive X-ray (EDX) compositional mapping revealed agglomeration of Pt nanoparticles around the top edges of CNWs. The degradation mechanism of Pt-CNWs under potential application with H 2 O 2 is discussed by focusing on the behavior of OH radicals generated by the H 2 O 2 reduction.