Polybenzimidazole and polybenzimidazole/MoS2 hybrids as an active nitrogen sites: hydrogen generation application

Abstract

Development of free metal or non-noble-metal catalysts for electrode materials with both excellent activity and high stability is essential for hydrogen production. In this work, nitrogen rich polybenzimidazole (PBI) networks were synthesized through a one-step polycondensation of 1,2,4,5-tetraaminobenzene with 4,4′,4′′-((1,3,5-triazine-2,4,6-triyl)tris(azanediyl))tribenzoic acid. Then, organic/inorganic nanohybrids of PBI with amorphous MoS₂ nanoplates (PBI–MoS₂) were prepared. The structural characterization and morphological of these novel hybrids were studies using FT-IR, ¹H NMR, elemental analysis, thermogravimetry, transmission electron microscopy, field-emission scanning electron microscopy and X-ray diffraction techniques. Electrochemical studies revealed the onset potential of only (−160 mV vs. RHE) with a small Tafel slope of 50.6 mV dec⁻¹ for hydrogen generation reaction in 0.5 mol L⁻¹ H₂SO₄. Stability tests through long term potential cycles confirm the excellent durability of PBI–MoS₂ in acid media. The outstanding hydrogen generation activity is derived from the electronic penetration effect and H⁺ absorption of pyridinic-N and/or pyrrolic-N as active sites at per repeat of the PBI matrix. It is worth noting that pure PBI and PBI–MoS₂ hybrids, for the first time, were used as both anode and cathode in two-electrode system open up new possibilities for exploring overall hydrogen generation technology catalysts in acidic electrolyte. This development offers an attractive electrocatalyst for large-scale hydrogen generation.