Photocatalytic H2 evolution measurements

In order to study the hydrogen evolution activity and stability of the designed photocatalyst, the experiment of photocatalytic hydrogen production by water splitting was carried out (Perfect Light Labsolar-6A high air tightness photocatalytic analysis system). Specifically, dispersing 20 mg sample powder into 100 ml aqueous solution (10 ml lactic acid and 90 ml deionized water). Equipping with a 300 W Xenon lamp (Perfect Light PLS-SXE300) as the light source, and using the optical filter (λ > 420 nm) to obtain the visible light. Before starting reaction, fill the hydrogen production equipment with high-purity nitrogen (N₂) for half an hour to remove the air in the reaction unit. The temperature of the system was maintained at 10°C using a low-temperature thermostat bath (DC-0506). The hydrogen production equipment is connected with GC9790II gas chromatograph to detect the amount of hydrogen. To achieve the apparent quantum efficiency (AQE), band-pass filter (PLS-BP20420, FWHM = 21 nm) was employed under a 300 W Xe lamp (Perfect Light PLS-SXE300). For the measurement of STH efficiency, the standard AM1.5 G filter was employed under a 300 W Xe lamp (Perfect Light PLS-SXE300). Use pl-ms-2000 optical power meter to measure the optical power density (P).

For 0.5 wt%, 1 wt%, 3 wt%, 5 wt% Pt/CdS, we used the in situ photo-deposition method. First, CdS was dispersed in a mixed solution of water and lactic acid, and then a certain amount of 0.003 g mL⁻¹ chloroplatinic acid (H₂PtCl₆·6H₂O) solution was added with a pipette, and irradiated with a full-spectrum Xenon lamp for half an hour. Hydrogen production test method is the same as above.

The AQE can be calculated by Eq. 9, and the meaning and value of each parameter is shown in Supplementary Table ⁹.

The STH efficiency can be calculated by Eq. 10:

Where R(H₂) is the photocatalytic hydrogen evolution rate (20 mg, mmol s⁻¹), ∆Gr is the molar Gibbs free energy of water splitting reaction (237 kJ mol⁻¹), P_sun is the optical power density of the AM1.5 G standard solar spectrum (100 mW cm⁻²), S is the irradiation area (19.6 cm²), the STH efficiency is calculated to be 3.83%.