Crystal-Phase and Surface-Structure Engineering of Bi2O3 for Enhanced Electrochemical N2 Fixation to NH3,ACS Applied Materials & Interfaces

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Crystal-Phase and Surface-Structure Engineering of Bi2O3 for Enhanced Electrochemical N2 Fixation to NH3
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2024-03-29 , DOI: 10.1021/acsami.4c00162
Pengju Guo ₁ , Fengxiang Yin _{1,

2} , Jie Zhang _{2,

3} , Biaohua Chen ₁ , Ziyang Ni ₁ , Liuliu Shi ₁ , Mengyan Han ₁ , Zumai Wu ₁ , Guoru Li _{1,

2}

Affiliation

The nitrogen reduction reaction (NRR) for ammonia synthesis is hindered by weak N₂ adsorption/activation abilities and the hydrogen evolution reaction (HER). In this study, αBi₂O₃ (monoclinic) and βBi₂O₃ (tetragonal) were first synthesized by calcination at different temperatures. Experiments and calculations revealed the effects of Bi₂O₃ with different crystal phases on N₂ adsorption/activation abilities and HER. Then, αBi₂O₃-x and βBi₂O₃-x series catalysts with surface oxygen vacancies (OVs) and Bi⁰ active sites were synthesized through the partial in situ reduction method. The results demonstrate the following: (I) Tetragonal βBi₂O₃ can better adsorb N₂ and cleave the N≡N bond, thereby obtaining a lower NRR rate-limiting energy barrier (*N≡N → *N≡N–H, 0.51 eV). Meanwhile, βBi₂O₃ can effectively suppress HER by limiting proton adsorption (H⁺ + e^– → *H, 0.54 eV). Therefore, βBi₂O₃-x series catalysts exhibit higher NH₃ yield and FE than αBi₂O₃-x. Meanwhile, in situ FTIR further confirms that βBi₂O₃ could better adsorb/activate N₂, and the NRR distal mechanism occurs on the Bi₂O₃ surface. (II) The introduction of NaBH₄ promotes the conversion of part of Bi³⁺ on the Bi₂O₃ surface into Bi⁰ and releases OVs. The additional active sites (OVs and Bi⁰) enhance the overall catalyst’s adsorption/activation capacity for N₂, further increasing the NH₃ yield and FE. Meanwhile, semimetal Bi⁰ can effectively limit electron accessibility, thereby inhibiting the combination of charges and adsorbed protons, reducing the HER reaction and improving the FE of NRR. Therefore, the introduction of NaBH₄ effectively improved the NH₃ yield and FE of the αBi₂O₃-x and βBi₂O₃-x series catalysts. After optimization, the βBi₂O₃-0.6 catalyst has the best NRR performance (NH₃ yield: 51.36 μg h^–1 mg^–1_cat.; FE: 38.67%), which is superior to the majority of bismuth-based NRR catalysts. This work not only studies the effects of Bi₂O₃ with different crystal phases on N₂ and HER reaction but also effectively regulates the active components of Bi₂O₃ surface, thereby realizing efficient NRR to NH₃ reaction, which provide valuable insights for the rational design of Bi-based NRR electrocatalysts.

中文翻译：

Bi2O3 的晶相和表面结构工程增强 N2 电化学固定到 NH3

用于氨合成的氮还原反应(NRR)受到弱N ₂吸附/活化能力和析氢反应(HER)的阻碍。在本研究中，首先通过在不同温度下煅烧合成了αBi ₂ O ₃ （单斜晶系）和βBi ₂ O ₃ （四方晶系）。实验和计算揭示了不同晶相的Bi ₂ O ₃对N ₂吸附/活化能力和HER的影响。然后，通过部分原位还原方法合成了具有表面氧空位（OV）和Bi ⁰活性位点的αBi ₂ O ₃ - x和βBi ₂ O ₃ - x系列催化剂。结果表明：（I）四方晶系βBi ₂ O ₃可以更好地吸附N ₂并裂解NeqN键，从而获得较低的NRR限速能垒（*NeqN→*NeqN-H， 0.51 eV）。同时，βBi ₂ O ₃可以通过限制质子吸附来有效抑制HER（H ⁺ + e ^– → *H，0.54 eV）。因此，βBi ₂ O ₃ - x系列催化剂比αBi ₂ O ₃ - x表现出更高的NH ₃产率和FE。同时，原位FTIR进一步证实βBi ₂ O ₃可以更好地吸附/激活N ₂ ，并且NRR远端机制发生在Bi ₂ O ₃表面。 (II)NaBH ₄的引入促进Bi ₂ O ₃表面的部分Bi ³⁺转化为Bi ⁰并释放OV。额外的活性位点（OV和Bi ⁰ ）增强了催化剂对N ₂的整体吸附/活化能力，进一步提高了NH ₃产率和FE。同时，半金属Bi ⁰可以有效限制电子的可达性，从而抑制电荷与吸附质子的结合，减少HER反应，提高NRR的FE。因此，NaBH ₄的引入有效提高了αBi ₂ O ₃ - x和βBi ₂ O ₃ - x系列催化剂的NH ₃产率和FE。优化后，βBi ₂ O ₃ -0.6催化剂具有最佳的NRR性能（NH ₃产率：51.36 μg h ^–1 mg ^–1 _cat. ；FE：38.67%），优于大多数铋基NRR催化剂。。该工作不仅研究了不同晶相的Bi ₂ O ₃对N ₂和HER反应的影响，而且有效调控了Bi ₂ O ₃表面的活性组分，从而实现了高效的NRR到NH ₃反应，为N 2 和HER反应的研究提供了有价值的见解。 Bi基NRR电催化剂的合理设计。

更新日期：2024-03-29

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