Functional Nanostructuring for Efficient Energy Conversion and Storage
new possibilities in a wide range of energy related applications. Therefore, nanostructured materials are becoming increasingly important in the research community of energy conversion and storage and have attracted great attention in recent years. 4 6 It is safe to say that nanostructuring may hold the key to the new generations of such devices because it leads to unusual mechanical, electrical and optical properties endowed by confi ning or patterning the dimensions of materials in the nanometer scale. In some cases, the effects are simple consequences of size reduction and thus advanced strategies are developed to effectively downsize the materials. In more cases, the effects involve internally nanostructured materials with particular functions and emerging concepts are proposed to bridge the functional nanostructures and the underlying mechanisms. Combining advanced strategies and emerging concepts with bulk and surface properties to the overall behavior, one can envision more breakthroughs and staggering developments that are triggered by functional nanostructuring for energy conversion and storage. Therefore, we are delighted to present this special issue of Advanced Energy Materials "Functional Nanostructuring for Effi cient Energy Conversion and Storage" This issue is composed of invited contributions in the Third International Conference on the Challenges and Perspectives of Functional Nanostructures (CPFN) that took place in June 2016 in Ilmenau, Germany. The aim of the conference is to discuss functional nanostructuring and surface nano patterning as well as their micro nano integration in order to solve fundamental crosscutting research issues that are especially related to energy and electronic devices. During the conference, an important focus was placed on the advancement of effi cient energy conversion and storage, to which this special issue is dedicated. In total eight Reviews, one Progress Report, one Research News, and two Full Papers are included in the special issue, which cover different prominent and intriguing concepts and strategies of functional nanostructuring designed for achieving effi cient energy conversion and storage. This special issue shall be a timely opportunity to highlight exciting recent progresses in the related research areas. Effi cient energy conversion and storage involves complex objects such as electrifi ed solid/liquid or solid/ solid interfaces that nanostructures are coping with. Properties of these largely determine various characteristics that functional nanostructuring needs to achieve, and these characteristics are mostly crucial for the actual processes happening during reactions. As a result, deep understanding of relations between these complex objects and functional nanostructures is of paramount importance to realize high effi ciency for energy conversion and storage devices. This special issue highlights emerging concepts to understand the nature of complex energy systems and advanced strategies to obtain various characteristics through functional structuring. Combination of innovative concepts and advanced strategies can provide us comprehensive understanding of these relations thus insights into future development of the devices. Two emerging concepts are presented to illustrate the breadth of high quality works and the important roles that deep exploration of the properties of nanomaterials plays. Firstly, triboelectric nanogenerators (TENGs) have been recently invented as a highly effi cient, cost effective and easy Inevitable fossil fuel depletion has made utilization of renewable energy extremely important. The utilization of various renewable energy sources has enormous impact on social and economic life, which has directed a global trend towards sustainable development. In the US, the Department of Energy's goal for the cost of energy applications on electric grids to achieve 20% wind penetration is $100 kW h 1