Revealing ammonia quantification minefield in photo/electrocatalysis.

Photo/electrocatalytic ammonia synthesis-a low-carbon and sustainable process has developed fast over the past decade while the ammonia yields over state-of-the-art photo/electrocatalysts are still very moderate. Such low concentration of synthesized NH 3 brings about a challenge to the reliable quantification of the product in photo/electrocatalysis. Notably, we found that the quantitative detection of ammonia concentration below 0.2 ppm is error-prone, which is likely the case happening in the majority of photo/electrocatalytic NH 3 synthesis, thus arising concerns about the rationality and accuracy for low-concentration ammonia quantification in these processes. Herein, we discuss the methodology used and analyze the reliability of various detection methods for the detection of trace ammonia in aqueous media. By regulating the parameters of detection methods, the experimental detection limitation can be expanded from 0.2 ppm to 0.1 ppm, even lower. The challenges facing the detection of low concentration of ammonia in photo/electrocatalysis can be overcome by integration with multiple detection methods. According to the data presented, we also propose an effective criterion for precise quantification of ammonia, avoiding the unreasonable comparisons in photo/electrocatalytic ammonia synthesis.