Measurement of the influence of ambient ammonia on photocatalytic N2 reduction reaction using salicylate method

Abstract

Ammonia ($NH_3$) is used in various industries as an essential chemical in the modern industrial economy. The photocatalytic and electrochemical nitrogen reduction reaction is attracting attention as an alternative to the Haber-Bosch process which widely used to produce ammonia, because the reaction proceeds at room temperature and atmospheric pressure without emission of carbon dioxide. However, ambient ammonia in the air impedes the accurate evaluation of properties on these alternatives due to their low efficiencies.

In this thesis, it is experimentally demonstrated that it is hard to evaluate properties of catalysts for the photocatalytic nitrogen reduction reaction accurately due to the ambient ammonia. And the influence of ambient ammonia on electrochemical nitrogen reduction reaction was determined. In order to measure the precise ammonia background level, the influence of cuvettes is determined in the salicylate method. And the measurement error was further reduced through the optimized reaction time of 30 minutes. Therefore, we showed that the ammonia background level should be accurately measured for accurate evaluation of the catalyst properties before starting the investigation of photocatalytic or electrochemical $N_2$ reduction reaction.