片状NiFeCo-LDH-Ti_(6)C_(3.75)复合催化剂的制备及电催化析氧性能

Layered NiFeCo-LDH-Ti_(6)C_(3.75)Catalyst:Preparation and Performance for Oxygen Evolution Reaction

氧析出反应(OER)是电解水的关键反应,但其动力学过程缓慢,限制了电解水的快速发展。因此,设计和构筑高效的OER催化剂对电解水至关重要。本研究以硝酸钴、硝酸镍、硝酸铁、尿素及Ti_(6)C_(3.75)为原料,采用简单的一步水热法制备了片状Co2+离子掺杂的NiFe双金属氢氧化物偶联Ti_(6)C_(3.75)的(NiFeCo-LDH-Ti_(6)C_(3.75))OER催化剂。NiFeCo-LDH-Ti_(6)C_(3.75)催化剂呈片状堆叠结构,有利于暴露更多活性位点,引入Co2+和Ti_(6)C_(3.75)可以降低Ni、Fe位点的电子密度。得益于此,NiFeCo-LDH-Ti_(6)C_(3.75)催化剂表现出优异的OER活性,在20 mA·cm^(–2)电流密度下的过电势仅为290 mV,并且Tafel斜率低至87.84 mV·dec^(–1),具有较快的反应动力学。并且其电荷转移电阻较低,电荷转移速率较高。此外,NiFeCo-LDH-Ti_(6)C_(3.75)催化剂在20 mA·cm^(–2)条件下经过6000圈加速老化测试后过电势仅增加约7 mV,表现出卓越的循环稳定性。

Oxygen evolution reaction(OER)is the key reaction for water splitting,but its slow kinetics limitsits application.Therefore,rational design and construction of efficient OER catalysts are crucial for water splitting.Here,a Co2+ion doped NiFe layered double hydroxides coupled Ti_(6)C_(3.75)(NiFeCo-LDH-Ti_(6)C_(3.75))catalyst was prepared by a simple one-step hydrothermal method using cobalt nitrate,nickel nitrate,iron nitrate,urea,and Ti_(6)C_(3.75)as raw materials.NiFeCo-LDH-Ti_(6)C_(3.75)catalyst showed a lamellar stacking structure,which is facilitating exposing more active sites.Introduction of Co2+and Ti_(6)C_(3.75)reduced the electronic density of Ni and Fe sites of NiFeCo-LDH-Ti_(6)C_(3.75)catalyst.Benefiting from these features,the NiFeCo-LDH-Ti_(6)C_(3.75)catalyst exhibits excellent OER activity with an overpotential of merely 290 mV at a current density of 20 mA·cm^(–2)and a Tafel slope of 87.84 mV·dec^(–1)with faster reaction kinetics.NiFeCo-LDH-Ti_(6)C_(3.75)catalyst shows a relatively low charge transfer resistance,which means a fast charge transfer efficiency.Furthermore,after 6000 cycles of accelerated aging test at 20 mA·cm^(–2),the overpotential only increased~7 mV,indicating excellent cycle stability of NiFeCo-LDH-Ti_(6)C_(3.75).