Highly active MoS2/carbon electrocatalysts for the hydrogen evolution reaction - insight into the effect of the internal resistance and roughness factor on the Tafel slope.
Highly active MoS2/carbon electrocatalysts for the hydrogen evolution reaction - insight into the effect of the internal resistance and roughness factor on the Tafel slope.
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DOI：
10.1039/c6cp07416b
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发表时间：
2017-01
期刊：
影响因子：
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通讯作者：
A. Murthy;J. Theerthagiri;J. Madhavan;K. Murugan
中科院分区：
文献类型：
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作者：
A. Murthy;J. Theerthagiri;J. Madhavan;K. Murugan
二硫化钼（MoS 2）纳米材料是一种很有前途的非贵金属析氢电催化剂。合成了MoS 2/碳电催化剂，其中碳组分用于增强电子传输。采用Tafel阻抗法分析了不同碳载体对电子传递的影响。在所研究的电催化剂中，二硫化钼/碳纳米管电催化剂的析氢活性最高，塔菲尔斜率最低。Tafel分析表明，在MoS 2和MoS 2/碳电催化剂中，析氢反应通过Volmer-Heyrovsky机理发生，具有速率决定Heyrovsky步骤。在二硫化钼/Vulcan碳中观察到塔菲尔斜率随质量载荷的有序变化，并基于粗糙度因子测量研究了其原因。塔菲尔斜率对粗糙度因子的线性依赖性指向伴随的对质量传输的限制的增加。结果表明，增加粗糙度因子的电催化剂的好处是抵消增加塔菲尔斜率，因此需要设计一个最佳的HER电催化剂平衡粗糙度因子和塔菲尔斜率推导。
Molybdenum disulphide (MoS2) nanomaterials are promising non-precious-metal electrocatalysts for the hydrogen evolution reaction. MoS2/carbon electrocatalysts have been synthesized with the carbon component serving the purpose of enhancing electron transport. The impedance method of Tafel analysis has been employed to evaluate the efficiency of various carbon supports in aiding facile electron transport. A MoS2/carbon nanofiber electrocatalyst has been found to be the most active towards hydrogen evolution with the lowest Tafel slope among the investigated electrocatalysts. Tafel analysis indicates that the hydrogen evolution reaction occurs through the Volmer-Heyrovsky mechanism with a rate determining Heyrovsky step in the MoS2 and MoS2/carbon electrocatalysts. Orderly variation of the Tafel slope with the mass loading has been observed in MoS2/Vulcan carbon and the cause for this has been investigated based on roughness factor measurements. A linear dependence of the Tafel slope on the roughness factor points to a concomitant increase in the limitations on mass transport. The results show that the benefit of increasing the roughness factor of the electrocatalyst is counterbalanced by increasing the Tafel slope, and hence the need for designing an optimal HER electrocatalyst balancing the roughness factor and Tafel slope is deduced.