Figure 10.

a) The comparison of four urea detection methods. Reproduced with permission.^{[ 90 ]} Copyright 2023, Elsevier. b) Proposed quantitative steps of photo‐/electrocatalytic urea synthesis based on the M‐DAMO‐TSC method. Measurement data and corresponding standard curve of urea determined by b,c) DAMO‐TSC; d,e) HPLC; and f,g) NMR methods. Reproduced with permission.^{[ 92 ]} Copyright 2023, Wiley‐VCH. h) UV‐vis absorption spectra of 2.0 ppm urea with 5.0 ppm N₂H₄, NH₃, and NH₂OH quantified by diacetyl monoxime method. i) UV‐vis spectra of indophenol blue method for ammonia obtained after the decomposition of 2 ppm urea with 25 ppm metal ions, and j) the corresponding photography of color substance. Reproduced with permission.^{[ 90 ]} Copyright 2023, Elsevier.