Catalytic Application of a Zwitterionic Polymeric Network for Hydrogen Generation via Sodium Borohydride Methanolysis

Abstract

Hydrogen energy is widely regarded as one of the most promising alternatives to fossil fuels. This study focuses on the synthesis of an environmentally friendly zwitterionic polymer catalyst, Poly(Quaternized-2-diethylaminoethyl methacrylate) (P(Q-DMA)), was synthesized and evaluated for the first time as a metal-free catalyst in NaBH4 methanolysis for hydrogen production. Owing to its zwitterionic nature, P(Q-DMA) was designed to interact synergistically with methanol and sodium borohydride through multiple mechanisms, including ion-dipole, ion-ion, and hydrogen-bonding interactions. The structure-function relationship was investigated using surface analysis (BET, SEM and Zeta), chemical characterization (FTIR, TGA), and kinetic modeling. Systematic optimization revealed high catalytic efficiency, achieving a hydrogen generation rate (HGR) of 443.4 mL H-2 min(-1) gcat(-1) and a mass-specific HGR of 8868.4 mL H-2 min(-1) gcat(-1), with a low activation energy (Ea) of 19.91 kJ mol(-1). The polymer also exhibited good electrocatalytic activity (0.72 mA cm(-2) at 0.8 V in 1 M NaOH + 0.1 M NaBH4) and stable performance during NaBH4 electrooxidation. Importantly, zeta potential values shifted from + 13.1 mV before reaction to - 12.2 mV (unwashed) and - 8.43 mV (washed) after reaction, indicating surface modification by adsorbed borate species. These results highlight P(Q-DMA) as a promising biocompatible, metal-free catalyst for scalable hydrogen production and electrochemical applications, aligning with sustainable and clean energy goals.