Tong Jiaxin, Tan Pengfei, Zhai Huanhuan, Lu Kuan, Lu Man, Tang Yu-Feng, Liu Min, Liao Hanxiao, Xie Jianping, Pan Jun
State Key Laboratory for Powder Metallurgy, Central South University, Changsha, 410083, China.
School of Minerals Processing and Bioengineering, Central South University, Changsha, 410083, China.
Small. 2024 Nov;20(46):e2403865. doi: 10.1002/smll.202403865. Epub 2024 Aug 6.
Electrocatalytic nitrite (NO ) reduction to ammonia (NH) is a promising method for reducing pollution and aiding industrial production. However, progress is limited by the lack of efficient selective catalysts and ambiguous catalytic mechanisms. This study explores the loading of PdCu alloy onto oxygen defective TiO, resulting in a significant increase in NH yield (from 70.6 to 366.4 µmol cm h at -0.6 V vs reversible hydrogen electrode) by modulating localized electron density. In situ and operando studies illustrate that the reduction of NO to NH involves gradual deoxygenation and hydrogenation. The process also demonstrated excellent selectivity and stability, with long-term durability in cycling and 50 h stability tests. Density functional theory (DFT) calculations elucidate that the introduction of PdCu alloys further amplified electron density at oxygen vacancies (Ovs). Additionally, the Ti─O bond is strengthened as the d-band center of the Ti 3d rising after PdCu loading, facilitating the adsorption and activation of NO. Moreover, the presence of Ovs and PdCu alloy lowers the energy barriers for deoxygenation and hydrogenation, leading to high yield and selectivity of NH. This insight of controlling localized electron density offers valuable insights for advancing sustainable NH synthesis methods.
电催化将亚硝酸盐（NO₂⁻）还原为氨（NH₃）是一种减少污染和助力工业生产的很有前景的方法。然而，由于缺乏高效的选择性催化剂以及催化机理不明确，进展有限。本研究探索了将钯铜合金负载到氧缺陷的二氧化钛上，通过调节局部电子密度，使氨产量显著提高（相对于可逆氢电极，在-0.6 V时从70.6增加到366.4 μmol cm⁻² h⁻¹）。原位和操作过程研究表明，NO₂⁻还原为NH₃涉及逐步脱氧和氢化。该过程还表现出优异的选择性和稳定性，在循环测试和50小时稳定性测试中具有长期耐久性。密度泛函理论（DFT）计算表明，钯铜合金的引入进一步增强了氧空位（Ov）处的电子密度。此外，负载钯铜后，随着Ti 3d的d带中心升高，Ti─O键得到加强，有利于NO₂⁻的吸附和活化。此外，Ov和钯铜合金的存在降低了脱氧和氢化的能垒，从而实现了NH₃的高产率和选择性。这种控制局部电子密度的见解为推进可持续的NH₃合成方法提供了有价值的思路。
