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.