Transition Metal Nanomaterials: Synthesis And Application In Electrocatalysis

Hydrogen as an abundant, renewable clean fuel can replace fossil fuels in the future. Amonge the technologies of hydrogen preparation, the electrolysis of water received extensive attention and application due to its simple operation and high purity product, but required effective catalysts to lower the high overpotential. It has been widely reported that Pt catalysts are hydrogen evolution reaction（HER） electrodes and Ir O2/Ru O2 catalysts are oxygen evolution reaction（OER） electrodes, but their long-term use become a problem because of the high cost. Based on this, a lot of work has put into the exploration of non-noble metal catalysts. Researchs have shown that transition metal nanomaterials（including Fe, Co, Ni, Cu, Mo, W, Zn and Mn non-noble metals）exhibited superior catalytic activities and stabilities in the process of warer electrolysis,when regareded as the HER and OER catalysts, they show great potentials for application. The dissertation mainly focuses on preparation and electrocatalytic application of transition metal nanomaterials, the points are addressed as follows:1、We reported the growth of FeP nanorod arrays on carbon cloth（FeP NAs/CC） via low-temperature phosphidation. When used as a binder-free 3D hydrogen evolution cathode in acidic media, the Fe P NAs/CC exhibited high catalytic activity and good durability, it needed overpotentials of 58 m V to achieve current density of 10 m A/cm², this electrode is also able to perform in both neutral and alkaline solutions.2、We reported the use of commercial Ni-Fe foam as a 3D OER anode. This electrode exhibited an onset overpotential of 300 m V and needed overpotential of 320 m V to drive current density of 10 m A/cm². Remarkably, acid-etchad Ni Fe foam（AE-Ni Fe foam） required overpotential of only 257 m V to reach 20 m A/cm².3、We presented our results on developing Zn_0.76Co)（0.24）S/CoS₂ nanowires array on Ti mesh（Zn-Co-S/TM） as a durable bifunctional catalyst for efficient electrochemical splitting of water in alkaline electrolytes. The Zn-Co-S/TM was topotactically derived from Zn Co2O4 nanowires array hydrothermally grown on Ti mesh（Zn Co2O4/TM）. Our Zn-Co-S/TM electrode exhibited high activity, with 20 m A/cm² at 238 m V HER overpotential and 20 m A/cm² at 330 m V OER overpotential. We further demonstrated a two-electrode alkaline water-splitting system based on Zn-Co-S/TM with an applied cell voltage of 1.66 V to afford 10 m A/cm².4、We reported the rapid development of an amorphous Ni-B alloy nanoparticle film on Ni foam（Ni-B/Ni foam） within minutes via alternately dipping deposition at room temperature. When used as a 3D catalytic electrode,this Ni-B/Ni foam was efficient and durable for both the OER and HER in alkaline electrolyte, with the need of a 360 m V overpotential to drive 100 m A/cm² for the OER and 125 m V overpotential to drive 20 m A/cm² for the HER. The two-electrode alkaline electrolyzer displayed 15 m A/cm² water-splitting current at a cell voltage of 1.69 V.