Hierarchical SixZr1−xMgO Monolithic Heterojunctions for Efficient Photocatalytic Hydrogen Evolution

Abstract

The production of green hydrogen (H₂) is a sustainable approach to addressing the current energy crisis without contributing to long-term greenhouse gas emissions. Many semiconductors based photocatalysts have shown great promise for light-driven H₂ generation. However, nanostructured powder form suffers from slow electron transfer kinetics, material loss, poor recyclability, and non-uniform light distribution, resulting in inconsistent hydrogen production performance. In this work, interface-mediated hierarchical heterojunctions, designed as a stable and efficient photocatalytic scaffold for solar hydrogen production and investigate their performance and structural stability by examining a series of Si_xZr_1−xMgO photocatalysts. A hydrogen generation yield of 694 μmol cm⁻² h⁻¹ was obtained for Si_0.9Zr_0.1MgO which is approximately 9 times higher than that of Si_0.1Zr_0.9MgO (76 μmol cm⁻² h⁻¹). The system maintained high H₂ production activity after 7 h of irradiation, demonstrating excellent stability and potential for practical applications. The enhanced photocatalytic performance of Si_0.9Zr_0.1MgO is attributed to its oxygen-vacancy-rich heterojunction structure, which improves visible-light absorption, facilitates charge separation, and accelerates interfacial electron transfer, thereby promoting efficient photocatalytic H₂ evolution. The concept of interface-mediated hierarchical heterojunctions introduces a novel strategy for structural and functional optimization in multi-component photocatalysts. This work highlights a promising strategy for designing next-generation, earth-abundant photocatalysts for scalable solar-to-hydrogen conversion applications.