Energy has been regarded as a central societal issue with tremendous impacts on global economy, environment and our daily life [1–۶]. With rapid development of modern society and increased population, the annual worldwide energy consumption is estimated to be 46 trillion watts by the end of twenty-first century. At present, most energy supply comes from fossil fuels, like oil (35%), coal (23%) and natural gas (21%) [7]. Such over-reliance results in deterioration of climate and environment. Limited resources cannot satisfy the ever-increasing energy requirements. Itis essentialto develop noveltechnologies on conversion and storage of renewable energy, which would be expected to be more practical and price-competitive with fossil fuels in future. Electrochemical energy conversion and storage technologies can convert energy into widely-used and practicable chemical energy or electrical energy, and store/release them replying on common redox electrochemical principles with little or no pollution. Hence, they stand out as the most viable option for eventual [8]. Although rapid development of research in this area, corresponding commercialization suffer from unsatisfied performance, such as durability, operability etc. [1,2,9]. Generally, innovation of materials lies at the heart in pursuit of further breakthroughs in electrochemical devices. Present commercial devices are mainly constructed by a planar configuration [10,11], remaining much room for approaching the theoretical capabilities of energy conversion and storage. To break this obstacle, heterogeneous nanostructure arrays, i.e. large-scale alignment of oriented nano-units that compose of more than one constituent on the substrate, have attracted intensive attention and exhibited excellent superiorities over the conventional counterparts. First, heterogeneous nanostructure arrays contain the tunable units in the nano-scaled dimensionality, which possess unusual physical and chemical properties due to the confining effects and large surface-to-volume ratio. The combination of surface and bulk properties to the entire behaviors is beneficial during electrochemical processes [1]. Second, the unit with fixed spatial orientation and high regularity can be assembled into large-scale array alignment and realize electrochemical energy conversion and storage at nanoscale independently without interrupting the electrochemical reactions in other units [6,9,10,12].Itis of significance to investigate electrochemical processes macroscopically for further microscopic optimization of energy conversion and storage devices. Third, heterogeneous nanostructure arrays, compared with homogeneous architectures, combine the advantages of different constituents and achieve the synergistic (“۱ + ۱ > 2”) performance through the strong interactions among different constituents [13]. Such material basis thus offers a versatile platform to potentially push forward the research on electrochemical energy conversion and storage, and further intrigues the design of single unit device electrode with multifunction. As known, properties of an ensemble of arrayed heterogeneous nanounits are intimately connected to the designed constituents and their interconnections within and among each individual unit. Despite the electrochemical applications differ from each other,the fundamental principle of construction is similar. Looking through previous reports on heterogeneous nanostructure arrays, we find that there are three basic working modes according to the roles in the final electrochemical devices. The first mode is called ‘FunctionFunction’, where different constituents play the same functional role at one time. If one constituent possesses the main electrochemical function, while other constituents can adjust related properties of functional constituent to assist the main function, this mode can be regarded as ‘Function-Assistance’. In both modes, it is worth mentioning that heterogeneous nanostructure arrays complete only one function, and additional functional constituents are also necessary to complete the entire circuit of the final electrochemical devices. Keeping this in mind, researchers also devote efforts to ‘Single-unit device’, where each unit serves as an independent electrochemical device. Within a single unit, different constituents with separated functions can work together to complete the construction of final devices in nanoscale.