Designing transition metal alloy nanoparticles embedded hierarchically porous carbon nanosheets as high-efficiency electrocatalysts toward full water splitting.

Developing high-efficiency catalysis electrodes towards both HER (hydrogen evolution reaction) and OER (oxygen evolution reaction) is critical to the popularity and practical application of devices for conversion and storage of clean and renewable hydrogen energy by overall water splitting. In this paper, a series of transition metal alloy nanoparticles embedded hierarchically porous carbon nanosheets (denoted as Fe _x Co _y @PCNSs) have been successfully designed and synthesized. After optimizing the metallic contents in Fe _x Co _y alloy, Fe ₃ Co ₇ @PCNSs displays superior water electrolysis performances compared to other control samples and previously reported non-noble metal catalysts. This advance is mainly due to the synergistic effect of increased carbon edges exposure, abundant accessible active sites, and improved electron/mass transport capability of 3D hierarchically porous architecture. More importantly, when Fe ₃ Co ₇ @PCNSs is applied as both cathode and anode in a two-electrode cell for carrying out the overall water splitting process, it just needs the corresponding cell voltages of 1.667 and 1.707 V to attain the 10 and 20 mA cm ^-2 current densities respectively. The synthesis of Fe ₃ Co ₇ @PCNSs confirms the importance of Fe and Co elements in designing catalyst structures. The electrochemical measurements further display the key roles of structural features and metal alloy@C active sites for boosting water splitting performances.
(Copyright © 2018. Published by Elsevier Inc.)