▎ 摘　　要

The outstanding properties of two-dimensional materials such as graphene offer the possibility to produce novel hybrid materials with boosted functionality for use in catalysis and electrochemical energy storage. The hydrogen evolution reaction and interfacial capacitance performance of monolayer graphene sheets decorated with various metal nanoparticles are studied herein. Chemical vapor deposition grown graphene monolayer was decorated with Au and/or Pd nanoparticles, either on one side or both sides, forming single- or bi metal graphene heterostructures. These asymmetrically decorated graphene nanocomposites were characterized using high-resolution scanning transmission electron microscopy and 3D electron tomography. Electrochemical characterization reveals enhanced hydrogen evolution activity and outstanding capacitance for the resultant composite materials in comparison to pristine graphene and other recently developed graphene-based energy storage devices. (C) 2017 The Authors. Published by Elsevier Ltd.