Probing of the Noninnocent Role of P in Transition-Metal Phosphide Hydrogen Evolution Reaction Electrocatalysts via Replacement with Electropositive Si
Probing of the Noninnocent Role of P in Transition-Metal Phosphide Hydrogen Evolution Reaction Electrocatalysts via Replacement with Electropositive Si
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DOI：
10.1021/acs.chemmater.3c00460
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发表时间：
2023-07-10
影响因子：
8.6
通讯作者：
Kovnir，Kirill
中科院分区：
文献类型：
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作者：
Kong，Seongyoung;Singh，Prashant;Kovnir，Kirill
过渡金属磷化物（TMP）已被认为是析氢反应（HER）的有前途的电催化剂。尽管最近的计算研究发现 P 位点对于氢吸附至关重要，但 TMP 优化的主要模式一直集中在改变金属位点。为了通过实验验证计算假设并为三元化合物的HER电催化剂优化提供途径，我们对结构相关的NiSi1–xPx相（即Ni2SiP、Ni5Si2P3、Ni3SiP2和Ni7Si2P5）进行了系统的实验研究，它们是NiSi结构的有序衍生物（Pnma、oP-8、MnP结构类型）。我们发现，P 在酸性电解质中调节 HER 活性方面发挥着重要作用，因为 NiSi 中 P 的掺入降低了电流密度 j= 10 mA/cm2 下的过电势，从 η10= 529 mV (NiSi) 降低到 η10= 97 mV (Ni2SiP)。 Ni2SiP 在活性和稳定性方面均优于当前在相同条件下制备和研究的最先进的 Ni5P4 电催化剂，这归因于结构中共价 Ni-Si 键的存在。在三元 Ni-Si-P 化合物家族中，电催化活性与费米能下 Ni-3d 态的数量相关。
Transition-metal phosphides (TMP) have been identified as promising electrocatalysts for the hydrogen evolution reaction (HER). Despite recent computational investigations identifying P sites as being crucial for hydrogen adsorption, the main mode of optimization forTMPs has been focused on changing the metal sites. To experimentally verify computational hypotheses and provide a route for HER electrocatalyst optimization via ternary compounds, we performed systematic experimental studies of structurally related NiSi1–xPxphases, namely, Ni2SiP, Ni5Si2P3, Ni3SiP2, and Ni7Si2P5, which are ordered derivatives of the NiSi structure (Pnma,oP-8, MnP structure type). We found that P played a significant role in modulating HER activity in an acidic electrolyte because the incorporation of P in NiSi reduced the overpotential at current densityj= 10 mA/cm2from η10= 529 mV (NiSi) to η10= 97 mV (Ni2SiP). Ni2SiP outperformed the current state-of-the-art Ni5P4electrocatalyst prepared and studied in identical conditions both in terms of activity and stability, which is attributed to the presence of covalent Ni–Si bonding in the structure. Within the family of ternary Ni–Si–P compounds, electrocatalytic activity correlates with the number of Ni-3dstates at the Fermi energy.