Shamloofard Maryam, Shahrokhian Saeed
Department of Chemistry, Sharif University of Technology, Tehran11155-9516, Iran.
Inorg Chem. 2023 Jan 23;62(3):1178-1191. doi: 10.1021/acs.inorgchem.2c03529. Epub 2023 Jan 6.
Increasing demands for pollution-free energy resources have stimulated intense research on the design and fabrication of highly efficient, inexpensive, and stable non-noble earth-abundant metal catalysts with remarkable catalytic activity for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Morphology control of the catalysts is widely implemented as an effective strategy to change the surface atomic coordination and increase the catalytic behavior of the catalysts. In this study, we have designed a series of Mn-Co catalyts with different morphologies on the graphite paper substrate to enhance OER and HER activities in alkaline media. The prepared catalysts with different morphologies were successfully obtained by adjusting the amount of ammonium fluoride (NHF) in the hydrothermal process. The electrochemical tests display that the cubic-like Mn-Co catalyst with pyramids on the faces at a concentration of 0.21 M NHF exhibits the best activity toward both OER and HER. The cubic-like Mn-Co catalyst with pyramids on the faces showed overpotentials of 240 and 82 mV at a current density of 10 mA cm for OER and HER, respectively. Also, the cubic-like Mn-Co catalyst with pyramids on the faces required overpotentials of 319 and 216 mV to reach the current density of 100 mA cm for OER and HER, respectively. The current density of this catalyst at η = 0.32 V was 701.05 mA cm for OER, and for HER, the current density of the catalyst was 422.89 mA cm at η = 0.23 V. The Tafel slopes of the Mn-Co catalyst with cubic-like structures with pyramids on the faces were 78 and 121 mV dec for OER and HER, respectively. A two-electrode overall water electrolysis system using this bifunctional Mn-Co catalyst exhibited low cell voltages of 1.60 in the alkaline electrolyte at the standard current density of 10 mA cm with appropriate stability. These electrochemical merits exhibit the considerable potential of the cubic-like Mn-Co catalyst with pyramids on the faces for bifunctional OER and HER applications.
对无污染能源资源的需求不断增加，刺激了人们对设计和制造高效、廉价且稳定的非贵金属富稀土金属催化剂的深入研究，这些催化剂对析氧反应（OER）和析氢反应（HER）具有显著的催化活性。催化剂的形貌控制作为一种有效的策略被广泛应用，以改变表面原子配位并提高催化剂的催化性能。在本研究中，我们在石墨纸基底上设计了一系列具有不同形貌的Mn-Co催化剂，以增强其在碱性介质中的OER和HER活性。通过在水热过程中调节氟化铵（NHF）的用量，成功制备了具有不同形貌的催化剂。电化学测试表明，在0.21 M NHF浓度下制备的表面带有棱锥的类立方Mn-Co催化剂对OER和HER均表现出最佳活性。表面带有棱锥的类立方Mn-Co催化剂在电流密度为10 mA cm时，OER和HER的过电位分别为240和82 mV。此外，表面带有棱锥的类立方Mn-Co催化剂在电流密度达到为100 mA cm时，OER和HER分别需要319和216 mV的过电位。该催化剂在η = 0.32 V时OER的电流密度为701.05 mA cm，在η = 0.23 V时HER的电流密度为422.89 mA cm。表面带有棱锥的类立方结构Mn-Co催化剂的Tafel斜率在OER和HER中分别为78和121 mV dec。使用这种双功能Mn-Co催化剂构建的两电极全水电解系统在碱性电解液中，在标准电流密度为10 mA cm时表现出低至1.60的电池电压以及适当的稳定性。这些电化学优点表明表面带有棱锥的类立方Mn-Co催化剂在双功能OER和HER应用中具有巨大潜力。
