The Electroactive Cobalt Materials Based On Silicon Microchannel Plates For Hydrogen Evolution Reaction

The silicon microchannel plate with high aspect ratio and large surface area,as the substrate layer of three-dimensional excellent electrode has broad protential in the hydrogen evolution reaction(HER)application.A series of MEMS processes were used to obtain the standard silicon microchannel plate(square pore size of 5?m×5?m,the depth is about 250?m)Firstly,cobalt-nickel-phosphorus alloy materials are deposited in the micro-channel of silicon microchannel plates(CoNiP/SiMCPs)with a drop flowing deposition method,formed cobalt-nickel-phosphorus micro-tubes arrays.Chemical deposition in vacuum is also employed to deposit CoNiP in the channel of SiMCPs for comparison.Secondly,the electrochemical characteristics of CoNiP/SiMCPs in an alkaline electrolyte are studied.The CoNiP/SiMCPs electrode exhibits efficient catalytic activity in the hydrogen evolution reaction(HER)under rapid stirring at a speed of 550 r/min.The overpotential required for a current density of 20 mA cm-2 is as small as-229 mV in the alkaline solution.The electrode shows a Tafel slope of 139.2-98.8 mV dec-1 and deceases in lmol L-1 KOH when the stirring speed is increased from 0 to 550 r/min.Compared with the 2D structure(CoNiP/Si),the 3D amorphous structure delivers better HER performance and has a large potential space in energy related applications.Conducting the HER using a non-precious transition metal hydroxide catalyst with high efficiency is challenging.For further exploration,we investigate HER activity achieved using three-dimensional(3D)tetsubo-like Co(OH)2 nanorods on a macroporous silicon electrically conductive network(MECN)synthesized by a hydrothermal method.The 3D array structure with a large aspect ratio provides a large specific surface area and exposes more active sites to catalyze electrochemical reactions at the electrode-electrolyte interface.Compared with Co(OH)2 nanosheets on an MECN and foamy Co(OH)2 on an MECN structure,the synthesized architecture has excellent HER catalytic reactivity,including a low potential of-69.2 mV vs.RHE,a cathodic current density of 10 mA cm-2,a small Tafel slope of 61.9 mV dec'1,a high current density,and robust catalytic stability in 1mol L-1 KOH,and is promising in HER applications.