Chavez Marcelo Eduardo, Biset-Peiró Martí, Murcia-López Sebastián, Morante Joan Ramon
Catalonia Institute for Energy Research (IREC), Jardins de les Dones de Negre 1, Sant Adrià de Besós 08930, Spain.
Facultat de Física, Universitat de Barcelona, C. Martí i Franqués, 1, Barcelona 08028, Spain.
ACS Sustain Chem Eng. 2023 Feb 22;11(9):3633-3643. doi: 10.1021/acssuschemeng.2c05885. eCollection 2023 Mar 6.
Transition metals, such as titanium (Ti) and copper (Cu) along with their respective metal oxides (TiO, CuO, and CuO), have been widely studied as electrocatalysts for nitrate electrochemical reduction with important outcomes in the fields of denitrification and ammonia generation. Based on this, this work conducted an evaluation of a composite electrode that integrates materials with different intrinsic activities (i.e., Cu and CuO for higher activity for nitrate conversion; Ti for higher faradaic efficiency to ammonia) looking for potential synergistic effects in the direction of ammonia generation. The specific performance of single-metal and composite electrodes has shown a strong dependence on pH and nitrate concentration conditions. Faradaic efficiency to ammonia of 92% and productivities of 0.28 mmol ·cm·h at 0.5 V vs reversible hydrogen electrode (RHE) values are achieved, demonstrating the implicit potential of this approach in comparison to direct NRR with values in the order of μmol ·h·cm. Finally, the electrochemical rate constants () for Ti, Cu, and CuO-Cu/Ti disk electrodes were determined by the Koutecky-Levich analysis with a rotating disk electrode (RDE) in 3.02 × 10, 3.88 × 10, and 4.77 × 10 cm·s demonstrating an apparent synergistic effect for selective NiRR to ammonia with a CuO-Cu/Ti electrode.
过渡金属，如钛（Ti）和铜（Cu）及其各自的金属氧化物（TiO、CuO和Cu₂O），作为硝酸盐电化学还原的电催化剂已被广泛研究，在反硝化和氨生成领域取得了重要成果。基于此，本工作对一种复合电极进行了评估，该复合电极整合了具有不同本征活性的材料（即Cu和CuO对硝酸盐转化具有较高活性；Ti对氨具有较高的法拉第效率），以期在氨生成方向上产生潜在的协同效应。单金属电极和复合电极的具体性能强烈依赖于pH值和硝酸盐浓度条件。在相对于可逆氢电极（RHE）为0.5 V时，实现了92%的氨法拉第效率和0.28 mmol·cm⁻²·h⁻¹的产率，这表明与直接硝酸盐还原反应（NRR）相比，该方法具有潜在优势，直接NRR的值仅为μmol·h⁻¹·cm⁻²量级。最后，通过旋转圆盘电极（RDE）的Koutecky-Levich分析确定了Ti、Cu和CuO-Cu/Ti圆盘电极的电化学速率常数（），分别为3.02×10⁻⁵、3.88×10⁻⁵和4.77×10⁻⁵ cm·s⁻¹，这表明CuO-Cu/Ti电极在选择性硝酸盐还原反应生成氨方面具有明显的协同效应。
