Sensitization of TiO<sub>2</sub>/g-C<sub>3</sub>N<sub>4</sub> Heterostructures via Pd–Au Cocatalysts: A Rational Design of Water Splitting System for Green Fuel Production
Kashaf Ul Sahar, Khezina Rafiq, Muhammad Zeeshan Abid, U. Rehman, Raed H. Althomali, Abdur Rauf, Ejaz Hussain
Abstract
The ecological impact and rising expenses of fossil fuels have led researchers to investigate alternative renewable-energy sources. Current work reported a novel and sustainable water splitting system comprising TiO 2 /Pd/Au integrated on g-C 3 N 4 surfaces. The phase purity and crystallization were analyzed by XRD, revealing characteristic patterns of TiO 2, g-C 3 N 4, and loaded Pd–Au cocatalysts. The electronic and structural properties were analyzed by Raman spectroscopy. The efficient charge separation in Pd/Au@g-C 3 N 4 /TiO 2 was demonstrated by PL spectral and TRPL analyses. Interface analysis, charge transfer resistance/capacitance, and dynamics were evaluated by EIS and temporal photocurrent responses. FTIR spectra indicate the interfacial connection between g-C 3 N 4 /TiO 2, while UV–vis/DRS revealed that Pd/Au@g-C 3 N 4 /TiO 2 exhibited superior optical absorption (absorption edge at 457 nm). The BET technique confirmed the mesoporous nature of Pd/Au@g-C 3 N 4 /TiO 2, while SEM demonstrated its lumpy surface morphology with high dispersion of cocatalysts. The elemental compositions and electronic states were further confirmed by EDX and XPS. Hydrogen evolution activities were conducted in the sunlight using a GC equipped with TCD. Activities indicated an encouraging rate of H 2 generation on fabricated g-C 3 N 4 /TiO 2 heterojunctions (Z-scheme interaction) having a Au-LSPR effect along with a Pd Schottky barrier impact. The maximum H 2 evolution rate of 36.51 mmol g –1 h –1 (Q.E = 10.46%) was applied with 5 mg of Pd/Au@g-C 3 N 4 /TiO 2 in the presence of triethanolamine pH 7.5. The durability of Pd/Au@g-C 3 N 4 /TiO 2 catalysts was assessed by recycling tests and optimized by experimental conditions. In the current work, the hydrogen evolved by Pd/Au@g-C 3 N 4 /TiO 2 was ≈11.23- and 6.97-fold higher than those by bulk TiO 2 (3.25 mmol g –1 h –1 ) and g-C 3 N 4 (7.87 mmol g –1 h –1 ), respectively. Based on the results, Pd/Au@g-C 3 N 4 /TiO 2 is recommended for reliable energy and fuel applications.