在 MnO2 上负载 IrOx 簇通过金属-载体相互作用促进酸性水氧化,ACS Applied Materials & Interfaces

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在 MnO2 上负载 IrOx 簇通过金属-载体相互作用促进酸性水氧化
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2023-09-29 , DOI: 10.1021/acsami.3c11038
Yunchu Zeng ₁ , Li Yan ₁ , Shubo Tian ₁ , Xiaoming Sun ₁

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贵金属基电催化剂对于有效氧化酸性水以开发绿色氢能至关重要。然而，负载在非活性基质上的传统贵金属催化剂显示出有限的固有催化活性，并且它们的大尺寸损害了这些贵金属的原子效率。在此，尺寸低于2 nm的IrO _x纳米团簇显示出Ir物质的高原子利用效率，被负载在具有不同相（α-MnO ₂、δ-MnO ）的氧化还原活性MnO ₂纳米基板（IrO _x /MnO _{2 ）上}₂和ε-MnO ₂ )探索最佳组合。电化学测量表明，IrO _x /ε-MnO ₂具有优异的 OER 性能，在 0.5 MH ₂ SO _{4中，10 mA cm}^–2下的过电位为 225 mV ，优于其对应物 IrO _x /α-MnO ₂ (242 mV) ) 和 IrO _x /δ-MnO ₂ (286 mV)。^{此外，它还具有强大的稳定性，在 10 mA cm –2}下连续工作 50 小时期间工作电位没有明显变化。_{结合XPS结果和Bader电荷分析，我们证明IrO x} /ε-MnO ₂的强金属-载体相互作用可以有效调节活性Ir原子的电子结构并稳定载体上的IrO _x纳米团簇以抑制其脱离，从而产生显着增强酸性 OER 的催化活性和稳定性。_{DFT 计算进一步支持 IrO x} /ε-MnO ₂催化 OER 性能的增强可归因于活性 Ir 位点与电位决定步骤（*O 和 *OOH）调节的反应中间体之间适当的相互作用强度通过氧化还原活性底物。

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Loading IrOx Clusters on MnO2 Boosts Acidic Water Oxidation via Metal–Support Interaction

Noble metal-based electrocatalysts are crucial for efficient acidic water oxidation to develop green hydrogen energy. However, traditional noble metal catalysts loaded on inactive substrates show limited intrinsic catalytic activity, and their large sizes have compromised the atom efficiency of these noble metals. Herein, IrO_x nanoclusters with sizes below 2 nm, displaying high atom-utilization efficiency of Ir species, were supported on a redox-active MnO₂ nanosubstrate (IrO_x/MnO₂) with different phases (α-MnO₂, δ-MnO₂, and ε-MnO₂) to explore the optimal combination. Electrochemical measurements showed that IrO_x/ε-MnO₂ had excellent OER performance with a low overpotential of 225 mV at 10 mA cm^–2 in 0.5 M H₂SO₄, superior to its counterpart, IrO_x/α-MnO₂ (242 mV) and IrO_x/δ-MnO₂ (286 mV). Moreover, it also delivered robust stability with no obvious change in operating potential at 10 mA cm^–2 during 50 h of continuous operation. Combining the XPS results and Bader charge analysis, we demonstrated that the strong metal–support interactions of IrO_x/ε-MnO₂ could effectively regulate the electronic structures of the active Ir atoms and stabilize IrO_x nanoclusters on supports to suppress their detachment, resulting in significantly enhanced catalytic activity and stability for acidic OER. DFT calculations further supported that the enhanced catalytic OER performance of IrO_x/ε-MnO₂ could be ascribed to the appropriate strength of interactions between the active Ir sites and the reaction intermediates of the potential-determining step (*O and *OOH) regulated by the redox-active substrates.

更新日期：2023-09-29

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