Robust P–N heterojunction polymer nanocomposites: advanced pH-universal electrocatalysts for highly efficient and stable water-splitting hydrogen production

Abstract

When combined, P-type polyaniline (PANI) and N-type exfoliated molybdenum diselenide (MoSe₂) nanosheets form a P–N heterojunction at their interface that significantly enhances electrocatalytic performance. Herein, an organic–inorganic PANI/MoSe₂ composite with a P–N heterojunction interface was successfully developed as an efficient electrocatalyst for the hydrogen evolution reaction (HER) under universal pH conditions. This newly developed system demonstrates exceptional long-term electrocatalytic stability in acidic, alkaline, and simulated seawater solutions and also shows promising potential to replace commercial noble metal platinum–carbon (Pt/C) catalysts in energy-related applications. The development of hydrogen energy is key in order to move toward net-zero carbon emissions; however, efficient, low-cost, pH-universal hydrogen evolution reaction (HER) catalysts remain a significant challenge. Organic polyaniline (PANI) and inorganic exfoliated molybdenum diselenide (MoSe₂) nanosheets are P-type and N-type semiconductors. Their combination facilitates formation of an organic–inorganic P–N heterojunction interface, which promotes efficient charge transfer from PANI to MoSe₂ and enhances HER catalysis under universal pH conditions. Here, we successfully constructed a MoSe₂/PANI composite catalyst with a P–N heterojunction interface and excellent electrocatalytic performance by integrating biopolymer-functionalized exfoliated MoSe₂ nanosheets with PANI on a conductive nickel foam (NF) substrate through electropolymerization and electroactivation. Compared to the commercial platinum–carbon catalyst, MoSe₂/PANI/NF exhibits superior electrocatalytic HER performance in acidic, alkaline, and simulated seawater electrolyte solutions, with similar Tafel slopes and lower overpotential and resistance values. Importantly, after 24 h of operation (100 mA cm⁻²) or 1000 cycles of cyclic voltammetry scanning in acidic and simulated seawater conditions, MoSe₂/PANI/NF demonstrated excellent catalytic stability and environmental tolerance, indicating potential to achieve efficient and highly stable water electrolysis for hydrogen production. Therefore, this emerging system may enable the development of pH-universal, non-precious metal electrocatalysts for various energy applications.