A highly stable non-noble metal Ni2P co-catalyst for increased H2 generation by g-C3N4 under visible light irradiation
Nickel phosphide (Ni2P) was grown on a graphitic carbon nitride (g-C3N4) surface by annealing a mixture of g-C3N4, NiCl2, and NaH2PO2 at 400 °C for 2 h in an Ar atmosphere. During the annealing, Ni2P particles formed intimate interfaces with g-C3N4. As a result, charge transfer from photo-excited g-C3N4 to Ni2P was improved as demonstrated by the improved photocatalytic H2 generation (40.5 μmol h−1 g−1) compared to a physical mixture of Ni2P and g-C3N4 (trace H2 generation). Under optimal and identical experimental conditions, the H2 production rate on Ni2P-loaded g-C3N4 (2 wt%) is 82.5 μmol h−1 g−1, which is higher than that of Pt-loaded g-C3N4 (0.5 wt%) (72 μmol h−1 g−1). Impressively, Ni2P shows a highly stable H2 production activity despite being a non-noble metal co-catalyst. No activity loss occurs over repeated use and 24 h long-term H2 generation trials. In contrast, a pronounced reduction in H2 generation was observed for Pt-loaded g-C3N4 (0.5 wt%) over the same 24 hour trial period. Among their many advantages, including non-toxicity, low cost and natural abundance, Ni2P/g-C3N4 composites are a promising alternative for realizing efficient, long-lasting photocatalytic H2 production.