High Catalysis Activity of Cu₂O Microcrystals to the Electrochemiluminesence of Luminol and H₂O₂

Cuprous oxide (Cu₂O) is a classical p-type semiconductor with a direct band gap of 2.17 eV, which is wildly used for solar energy conversion, CO oxidation, and photo catalytic water splitting for the low cost and environmental friendliness. For the energy band positions are favorable to the hydrogen evolution and oxygen evolution potentials, Cu₂O materials also catalyze the reduction of hydrogen peroxide (H₂O₂), which is an critical molecule in the bodies’ metabolism processes or the industrial catalysis reactions. To improve detection sensitivity of H₂O₂, people have composed Cu₂O materials with Ag nanoparticles or graphene nanosheets, which are sophisticated and cost. Herein, we use the electrochemiluminescence (ECL) method to improve the sensitivity of the reaction catalyzed by Cu₂O microcrystals. As shown by Figure 1A, the ECL reaction of H₂O₂ and luminol catalyzed by Cu₂O octahedra (Figure 1B) is strong at the potential of – 0.2 V (vs. Ag/AgCl). And the corresponding current of the reaction is not obvious (Figure 1A, inset). We also check the effect of copper ions (Cu²⁺) to the ECL reaction, and there is much lower catalytic activity to the ECL reaction by Cu²⁺ ions. It indicates that Cu₂O semiconductor microcrystal possess the good catalytic performance to this ECL reaction, which is important to develop the high-efficient and lowcost biosensors.