GB/T 39359-2020 in English

GB/T39359-2020 has established a complete technical system for measuring the quantum efficiency of suspended photocatalytic hydrogen production reactions using an optical integrating sphere. Its innovation is reflected in:

• For the first time, a three-stage hydrogen production effect discrimination method (self-degradation/mechanical catalysis/photothermal catalysis) is proposed
• A precise spectral absorption measurement model based on Lambert's cosine law is established
• Strict technical requirements are set for the opening area of the integrating sphere ≤3% of the internal surface area

The quantum efficiency calculation formula proposed by the standard is:

η = (2×n_H2) / a_pc ×100%

Wherein:

• n_H2: number of hydrogen molecules produced per unit time (determined by gas chromatography)
• a_pc: number of effective photons absorbed by the photocatalyst (determined by integrating sphere method)

The case in Appendix C shows that at a wavelength of 360nm, the traditional apparent quantum efficiency measurement value is about 50% lower than the true value of the integrating sphere method, proving that this method can effectively avoid measurement deviations caused by light scattering losses.

1. System calibration: Before each experiment, the integrating sphere constant K value should be calibrated with a standard light source (Formula A.5)
2. Background subtraction: The three-stage blank experiment of self-degradation/mechanical catalysis/photothermal catalysis must be completed
3. Parameter control: The absorption parameter α of the reaction solution should be <0.1, and the transmittance change should be ≤5%/h
4. Data verification: The conversion number TON>1 can be determined as a photocatalytic reaction

Technology evolution analysis

Compared with the energy conversion efficiency calculation method of GB/T26915, this standard achieves the following through the optical integrating sphere:

• Measurement upgrade from apparent quantum efficiency to true quantum efficiency
• Multi-wavelength segmented measurement (300-1050nm) capability
• Dynamic compensation of optical path length change of liquid-solid suspension system (Formula 8)