Efficient solar-driven ammonia decomposition using economical K-Co3Mo3N catalyst at low temperatures

Abstract

Solar-driven ammonia decomposition suffers from either using expensive ruthenium catalysts or requiring a high operating temperature (>550 °C). Here, we report that this limitation can be overcome by using a K-modified Co3Mo3N catalyst constructed by a single-step nitridation of CoMoO4 and plentiful K2CO3. The optimal 0.864 %K-Co3Mo3N catalyst presents a conversion of 86.5 % and a hydrogen production rate of 347.5 mmol gcat−1⋅h−1 under conditions of 500 °C and a gas hourly space velocity of 6000 mL gcat−1⋅h−1, which is comparable to most of the reported Ru-based catalysts. Based on the results from density functional theory calculations, the step of desorbed N2 is with the highest energy barrier. The overall energy barrier computed is 0.54 eV, which is consistent with the experimentally measured activation energy. Further, a remarkable solar-to-fuel efficiency of 14.4 % is achieved. This work highlights the enhancement effect of K on Co3Mo3N for efficient solar-driven NH3 decomposition at low temperatures.