Plasma-derived hydrogen radical-mediated N2 activation for mild ammonia synthesis: insights into the importance of the oxygen vacancy on the reaction mechanism

Abstract

Plasma-catalytic NH3 synthesis has recently been recognized as a complementary route to the Haber–Bosch process for decentralized NH3 production. However, the activation of N2 in current plasma catalysis works is still followed the conventional heterogeneous reaction mechanism on catalyst surface, which does not take full advantage of the highly reactive species generated in the plasma, resulting in high energy consumption and low rate of NH3 production. Here, we present a distinctive hydrogen radical-mediated N2 activation pathway with an ultralow energy barrier of 0.123 eV for N2 activation. This strategy achieves highly efficient N≡N bond cleavage with activation by gaseous hydrogen radicals generated on an oxygen-deficient CeO2/CuO catalyst. With this strategy, we achieved an superhigh NH3 yield of 196.2 mg·h-1·g-1cat. under mild conditions. Our results illustrate the potential of exploiting plasma-derived hydrogen radicals as ideal and homogeneous activation agents for inert gas molecules and introduce a design strategy for catalysts that utilize oxygen vacancies to assist hydrogen radical generation.