Calcium-based multi-carboxylate linker metal organic framework for photocatalytic and electrocatalytic hydrogen production

Hydrogen (H₂) is a clean and sustainable energy carrier, offering high energy density and environmental benefits. However, efficient hydrogen production remains a challenge due to limitations in catalyst design, stability, and activity. Herein, we report the synthesis and evaluation of three calcium-based metal-organic frameworks (MOFs) Ca-BDC, Ca-BTC, and Ca-BTTC for photocatalytic and electrocatalytic hydrogen evolution. The structural and electronic properties of the MOFs were characterized using various analytical techniques, and their hydrogen evolution performance was assessed under visible light and electrochemical conditions. Ca-BDC exhibited the highest photocatalytic hydrogen production rate of 939.6 μ.mol /g/ h, attributed to its optimal bandgap and efficient electron transfer dynamics. In electrocatalysis, Ca-BTTC showed better stability and high turnover frequency (8.218 × 10 −3 mol H₂ s −1 at 159.80 mV overpotential), while Ca-BTC demonstrated fast reaction kinetics. The reduced photocatalytic efficiency of Ca-BTC and Ca-BTTC is linked to their higher carboxylic acid content, which limits electron transport and increases bandgap. These findings show the potential of calcium-based MOFs as versatile catalysts for hydrogen production and highlight the importance of linker design and carboxylic acid optimization in enhancing catalytic activity.