M-MOF-74（M=Ni,Co, Zn）的制备及其电化学催化合成氨性能

将自然界丰富的氮转化为氨对人类社会发展至关重要。以氮和水为原料的电化学合成氨是极具应用前景的绿色合成过程。采用水热法合成了Ni-, Co-和Zn-MOF-74催化剂，采用XRD、SEM以及XPS等表征了催化剂结构，并在0.1 mol·L^-1 Na₂SO₄电解液中研究了它们的电催化合成氨性能。结果表明，在常温常压下，Ni-MOF-74的电催化合成氨性能优于Co-和Zn-MOF-74催化剂，在-0.7 V (vs Ag/AgCl)下其氨合成速率和法拉第效率分别高达6.68×10^-11 mol·s^-1·cm^-2和23.69%，这归因于Ni-MOF-74不仅颗粒尺寸小且分布均匀，而且具有最多的金属-氧键和最大的电化学比表面。特别是Ni-MOF-74还能有效抑制析氢副反应，从而提高了法拉第效率。

Preparation of M-MOF-74 (M = Ni,Co, Zn) and its performance in electrocatalytic synthesis of ammonia

The conversion of nitrogen rich in nature into ammonia is vital to the development of human society. The electrochemical synthesis of ammonia using nitrogen and water as raw materials has been regarded as a promising and environmentally friendly process. In this work, Ni-, Co- and Zn-MOF-74 were prepared by hydrothermal synthesis, and were characterized by XRD, SEM and XPS. Their catalytic performance was investigated in 0.1 mol·L^-1 Na₂SO₄ electrolyte. The results show that Ni-MOF-74 has better electrocatalytic performance for ammonia synthesis than Zn- and Co-MOF-74 catalysts. Ni-MOF-74 can achieve the high NH₃ yield (6.68 × 10^-11mol·s^-1·cm^-2) and high Faraday efficiency (23.69%) at -0.7 V (vs Ag/AgCl). Ni-MOF-74 has not only the small particle size with uniform distribution, but also the greatest number of metal-oxygen bonds and the largest electrochemical specific surface. Specially, Ni-MOF-74 can effectively inhibit hydrogen evolution side effect, which results in enhanced the Faraday efficiency.