Efficient generation of singlet oxygen (1O2) by CoP/Ni2P@NF for degradation of sulfamerazine through a heterogeneous electro-Fenton process at circumneutral pH

In this study, the nano-needle-shaped CoP/Ni2P heterostructure were loaded onto a nickel foam substrate (CoP/Ni2P@NF), which was used as a cathode material for heterogeneous electro-Fenton (Hetro-EF) to degrade sulfamerazine (SMR) at circumneutral pH. Due to the self-regulation of pH and the efficient generation of singlet oxygen (1O2), the degradation rate of SMR can reach 100% and 87% at initial pH = 6.8 and 11, and the system has a wide range of pH application. Experimental and theoretical calculations demonstrated that the heterostructure of CoP/Ni2P redistributed the interfacial charge and accelerated the electron transfer, resulting in a 2e−ORR selectivity and activity of CoP/Ni2P different from that of CoP and Ni2P, which ensured the sustained generation of H2O2 and subsequently ROS. 1O2 was the main ROS in the system and 1O2 was converted from ·OH adsorbed on the catalyst surface. This study provides a promising catalytic material for the application of Hetro-EF to the removal of organic compounds in complex water under ring neutral conditions. [Display omitted] In electro-Fenton (EF), the development of a catalytic material with wide pH application range and high interference resistance is more suitable for practical wastewater treatment. In this study, the nanoneedle-shaped CoP/Ni2P heterostructure loaded onto a nickel foam substrate (CoP/Ni2P@NF) was successfully fabricated, which was used as a cathode material for heterogeneous electro-Fenton (Hetero-EF) to degrade sulfamerazine (SMR) at circumneutral pH. The SMR degradation efficiency within 90 min went to 100% and 87% at initial pH of 6.8 and 11, respectively. Experiments and theoretical calculations demonstrated that the heterostructure of CoP/Ni2P redistributed the interfacial charge and accelerated the electron transfer, resulting in different two-electron oxygen reduction (2e−ORR) selectivity and activity than CoP and Ni2P. The ion interference and complex water quality experiment exhibited that the degradation performance remained almost unchanged, showing better anti-interference ability and complex water quality applications. Through quenching experiments and EPR tests, it is confirmed that singlet oxygen (1O2) was the major reactive oxygen species (ROS) and 1O2 was converted from hydroxyl radical (·OH) adsorbed on the catalyst surface. This study provides an efficient catalyst for the application of Hetero-EF to remove organic compounds in complex water at circumneutral pH.