美国加州理工学院Peters, Jonas C.团队报道了通过质子耦合电子转移实现串联电催化固氮。相关研究成果于2022年8月31日发表在国际顶尖学术期刊《自然》。
新的电化学氨（NH3）合成技术作为哈伯-博世(Haber-Bosch)分布式肥料生产工艺的补充路线，以及利用氨作为通过可再生能源发电生产的零碳燃料，具有重要意义。与这些目标相对应的是，针对非均相材料作为氮还原反应(N2RR)电催化剂的基础研究激增。这些系统通常存在稳定性差和NH3选择性差的问题；析氢反应（HER）超过N2RR。分子催化剂系统可以精细调整并提供替代策略，但同样的选择性问题阻碍了进展；HER主宰一切。
该文中，研究人员报道了一种串联催化策略，为这一难题提供了解决方案。可介导N2还原循环的分子络合物与助催化剂合作，助催化剂将电极和酸连接起来，以介导质子耦合电子转移步骤，促进NH键在有利的施加电位（1.2V vs Fc+/0）和整体热力学效率下形成。N2RR循环的某些中间体将通过未耦合的电子转移或质子转移步骤而不反应。几种金属（W、Mo、Os、Fe）的结构多样的络合物也在存在介质的情况下在相同电位下介导N2RR电催化，这表明这种串联方法的普适性。
附：英文原文
Title: Tandem electrocatalytic N2 fixation via proton-coupled electron transfer
Author: Garrido-Barros, Pablo, Derosa, Joseph, Chalkley, Matthew J., Peters, Jonas C.
Issue&Volume: 2022-08-31
Abstract: New electrochemical ammonia (NH3) synthesis technologies are of interest as a complementary route to the Haber–Bosch process for distributed fertilizer generation, and towards exploiting ammonia as a zero-carbon fuel produced via renewably sourced electricity1. Apropos of these goals is a surge of fundamental research targeting heterogeneous materials as electrocatalysts for the nitrogen reduction reaction (N2RR)2. These systems generally suffer from poor stability and NH3 selectivity; the hydrogen evolution reaction (HER) outcompetes N2RR3. Molecular catalyst systems can be exquisitely tuned and offer an alternative strategy4, but progress has been thwarted by the same selectivity issue; HER dominates. Here we describe a tandem catalysis strategy that offers a solution to this puzzle. A molecular complex that can mediate an N2 reduction cycle is partnered with a co-catalyst that interfaces the electrode and an acid to mediate proton-coupled electron transfer steps, facilitating NH bond formation at a favourable applied potential (1.2V versus Fc+/0) and overall thermodynamic efficiency. Certain intermediates of the N2RR cycle would be otherwise unreactive via uncoupled electron transfer or proton transfer steps. Structurally diverse complexes of several metals (W, Mo, Os, Fe) also mediate N2RR electrocatalysis at the same potential in the presence of the mediator, pointing to the generality of this tandem approach.
DOI: 10.1038/s41586-022-05011-6
Source: https://www.nature.com/articles/s41586-022-05011-6