Sustainable Development Goals
Abstract/Objectives
As global energy demand rises and environmental challenges become increasingly urgent, pursuing sustainable alternative energy sources has become a critical focus. One promising approach is converting solar energy into hydrogen through water splitting, which leverages photocatalytic methods to harness solar light for decomposing water into hydrogen and oxygen. This method not only facilitates the efficient utilization of solar energy but also produces clean hydrogen fuel, an efficient energy carrier whose combustion byproduct is simply water, thereby significantly reducing greenhouse gas emissions. This project will explore the photocatalytic hydrogen evolution reaction (HER) using organic semiconductor photocatalysts, with Benzothiadiazole as the core material. The project will modify the electron-withdrawing functional groups on the core and electron-donating groups on the periphery, comparing the resulting materials regarding band gaps, optical properties, and photocatalytic hydrogen production performance to enhance efficiency and sustainability.
Results/Contributions

In this project, we designed and synthesized a series of benzothiadiazole-based electron-withdrawing compounds: DPASBT-2F, IDBSBT-2F, PXZSBT-2F, DPASBT-2CN, and IDBSBT-2CN. By tuning electron-donating and functional groups, their photophysical properties and energy levels were optimized.

Fluorinated compounds exhibited absorption from blue to green light, while cyano-substituted compounds covered the entire visible spectrum. Cyclic voltammetry and energy level calculations confirmed that replacing fluorine with the stronger electron-withdrawing cyano group lowered the LUMO level, reducing the energy gap and facilitating electron transfer for photocatalytic hydrogen evolution.

ICP-OES analysis revealed minimal palladium residue in PXZSBT-2F, which achieved a hydrogen evolution rate of 237.26 μmol h⁻¹ g⁻¹, demonstrating high HER efficiency without the requirement for a metal cocatalyst. Through new material design and optimization of photocatalytic processes, it is hoped that these organic small molecule photocatalytic materials will provide sustainable and scalable energy solutions for the future.

Keywords
Photocatalytic hydrogen evolution reaction Metal-free Small molecule Benzothiadiazole-based core