1：Experimental Design and Method Selection:

The study involved modifying CdWO4 with 4-MBA to create a polar surface and built-in electric field. Methods included hydrothermal synthesis, characterization techniques (XRD, TEM, FT-IR, XPS, TGA, DRS, PL, Voc, SHG), and photocatalytic activity tests for hydrogen evolution and RhB degradation.

2：Sample Selection and Data Sources:

Samples were synthesized using analytical grade reagents. CdWO4 was prepared from Na2WO4·2H2O and Cd(Ac)2·2H2O via hydrothermal method. 4-MBA@CdWO4 was synthesized by reacting CdWO4 with 4-MBA in water/DMF mixture under hydrothermal conditions.

3：List of Experimental Equipment and Materials:

Equipment included JEOL-2011 TEM, BRUKER D8 ADVANCE XRD, Nicolet Nexus 6700 FT-IR, Shimadzu UV 2550 DRS, Hitachi F-4500 PL spectrophotometer, time-correlated single photon counting module for time-resolved PL, Diamond TG-DTA, photomultiplier tube for SHG, PAR 263A potentiostat for Voc, gas chromatograph (ShiweipxGC-7806) for H2 evolution, and 300 W Xe arc lamp for photocatalytic tests. Materials included CdWO4, 4-MBA, Na2WO4·2H2O, Cd(Ac)2·2H2O, KI, H3PO2, DMF, RhB, and other chemicals.

4：Experimental Procedures and Operational Workflow:

Synthesis of CdWO4 involved hydrothermal reaction at 180°C for 24h. Synthesis of 4-MBA@CdWO4 involved hydrothermal reaction at 120°C for 24h after stirring with 4-MBA. Characterization was performed using the listed equipment. Photocatalytic hydrogen evolution was carried out in a top-irradiation vessel with catalyst suspension under UV-Vis light, measuring H2 with gas chromatography. Photocatalytic degradation of RhB was evaluated under similar conditions, measuring UV absorption.

5：4h. Synthesis of 4-MBA@CdWO4 involved hydrothermal reaction at 120°C for 24h after stirring with 4-MBA. Characterization was performed using the listed equipment. Photocatalytic hydrogen evolution was carried out in a top-irradiation vessel with catalyst suspension under UV-Vis light, measuring H2 with gas chromatography. Photocatalytic degradation of RhB was evaluated under similar conditions, measuring UV absorption. Data Analysis Methods:

5. Data Analysis Methods: Data from characterization techniques were analyzed to confirm material properties. Photocatalytic activity was quantified by H2 evolution rates and RhB degradation percentages. PL spectra and Voc measurements were used to assess charge separation efficiency.