Abstract:  The transition to sustainable energy solutions is crucial for meeting global energy demands and addressing climate change. Hydrogen is a promising clean energy carrier, but its efficient storage and release remain challenging. This study focuses on developing single-site ruthenium pincer catalysts for hydrogen production and storage using formic acid as a Liquid Organic Hydrogen Carrier (LOHC). By integrating homogeneous and heterogeneous catalysis through Surface Organometallic Chemistry (SOMC), this research advances catalyst design for clean hydrogen production.

The work explores the synthesis, immobilization, and characterization of ruthenium PN3P pincer complexes on silica supports, particularly Al-H@KCC-1 and SiO2-700. These supports enhance catalyst dispersion and stability. Spectroscopic and analytical techniques confirm successful grafting and investigate the electronic and structural properties of the catalysts.

Key findings highlight excellent catalytic performance in formic acid dehydrogenation, with turnover numbers (TON) of 600,000 and turnover frequencies (TOF) of 35,000 h-1. The immobilization of ruthenium pincer complexes improves catalyst stability and recyclability. Mechanistic studies reveal that silica surfaces stabilize reactive intermediates, enhancing hydrogen release via metal-ligand cooperation.

This research demonstrates the potential of tailored silica-supported catalysts for scalable hydrogen storage and CO2 utilization, contributing to sustainable energy solutions. The integration of SOMC with advanced pincer complexes represents a significant step toward energy sustainability and reducing the environmental footprint of hydrogen production.