The activation and degradation mechanism of Ni-LDH catalysts electrodeposited on low and high-density carbon papers for the oxygen evolution reaction (OER) in alkaline media was investigated using in situ X-ray absorption near-edge structure (XANES) spectroscopy coupled with CV cycles in a potential range of 0–0.9 V (vs Hg/HgO), which allowed proposing two-stage degradation mechanisms with respect to cyclic voltammetry (CV) cycles. The electrodeposited α-Ni(OH)₂ is firstly transformed to γ-NiOOH as an active phase in OER. In the reducible potential region, however, γ-NiOOH was partially reduced to β-Ni(OH)₂, isolating the rest, which is the first stage of degradation. In the following anodic potential region, β-Ni(OH)₂ is readily converted to β-NiOOH, which is mostly reversible, but only a small portion of β-NiOOH is overcharged to unstable γ-NiOOH, being responsible for the second stage degradation. It was noted that Ni(OH)₂ catalysts electrodeposited on a low-density carbon paper (Ni-LC) underwent a severe degradation in the first stage, losing at least 56.9 % current density at 0.65 V (vs Hg/HgO), followed by a steady degradation in the second stage, while the use of a high-density carbon substrate (Ni−HC) effectively improved redox stability, maintaining a minimal loss of overpotential less than 5%, particularly with the second stage degradation being negligible even under potential changes, providing an important insight into designing durable and active Ni-LDH catalysts for the OER.

利用原位X射线吸收近边缘结构（XANES）和CV技术研究了在低密度和高密度碳纸上电沉积Ni-LDH催化剂在碱性介质中的氧释放反应（OER）的活化和降解机理。在0-0.9 V（vs Hg / HgO）的电位范围内进行循环，这允许就循环伏安（CV）循环提出两阶段降解机理。电沉积的α-Ni（OH）₂首先在OER中转变为γ-NiOOH作为活性相。但是，在可还原电位区域，γ-NiOOH被部分还原为β-Ni（OH）₂，其余部分被隔离，这是降解的第一阶段。在以下阳极电势区域中，β-Ni（OH）₂β-NiOOH容易转化为大部分可逆的β-NiOOH，但只有一小部分β-NiOOH被过度充电至不稳定的γ-NiOOH，这是第二阶段降解的原因。值得注意的是，电沉积在低密度碳纸（Ni-LC）上的Ni（OH）₂催化剂在第一阶段经历了严重降解，在0.65 V（vs Hg / HgO）下损失了至少56.9％的电流密度，随后通过第二阶段的稳定降解，同时使用高密度碳基质（Ni-HC）有效改善了氧化还原稳定性，将过电势的最小损失保持在5％以下，尤其是第二阶段的降解可以忽略不计潜在的变化，为设计用于OER的耐用和活性Ni-LDH催化剂提供了重要的见识。