Ultrathin CuNi2Al-LDH nanosheets with enhanced electron transfer for visible-light-driven photo-fenton-like water decontamination

The Cu-based photo-Fenton-like process stands out as a promising technology for water decontamination, but its catalytic efficiency for refractory organic pollutants removal still suffers from shortage of Cu(I) supply in the activation of H2O2. Herein, we, for the first time, developed ultrathin nanosheets of Cu(I)-enrich CuNi2Al layered double hydroxides (CuNi2Al-LDH) with fast electron transfer rate to achieve superior visible-light-driven photo-Fenton catalytic performance. In the brucite-like sheets of LDH, the electron donation effect of Ni enabled the electron transfer from Ni to Cu, resulting in generation of 62.9 % Cu(I) content, which provided abundant Cu(I) active sites for Fenton-like reaction. Notably, the coexistence of Ni and Cu ions in the nanosheets significantly enhanced the visible-light harvesting ability by d-d transitions, thereby boosting the production of photogenerated carriers. More importantly, the Ni sites with excellent electroactivity served as electron-transfer mediators to remarkably promote the photogenerated carriers charge separation and photogenerated electrons transfer, leading to nearly 20 times improvement in the photocurrent density of CuNi2Al-LDH in comparison to the Ni-free LDH, which greatly expedited the Cu(II)/Cu(I) cycle and promoted H2O2 activation. Benefiting from these advantages, CuNi2Al-LDH could degrade 100 % of phenol, tetracycline (TC) and dyes within 30 min at room temperature through the synergy effect of photocatalysis and Fenton oxidation, and the reactive oxygen species •OH, •O2− and 1O2 contributed 44.2 %, 12.9 % and 37.7 % to the degradation of pollutants, respectively. This study provides an ingenious strategy to the rational design of on-demand multifunctional catalysts for advanced water remediation.