Facile and scalable synthesis of recyclable N,Se-doped CuO microrods of microsheets for highly efficient reduction of 4-nitrophenol

Abstract

CuO has been extensively utilized as a potential catalyst in the conversion of harmful 4-nitrophenol (4-NP) into valuable 4-aminophenol (4-AP). However, its intrinsic catalytic performance is greatly hindered by its poor electron transfer and durability. Therefore, it is crucial to produce high-performance CuO for this hydrogenation reaction. Herein, combining with a low-temperature selenization process, we use copper nitrate molten salts as a precursor to obtain recyclable N,Se-doped CuO on Ni foam on a large scale. As a result of the N,Se-doping, this catalyst possesses better dispersion, more accessible active sites and favorable electron transport. With a low molar ratio of 10 between NaBH₄ and 4-NP, the optimal N,Se-doped CuO exhibits excellent catalytic activity for 4-NP reduction. It has a lower activation energy of 28.23 kJ mol⁻¹ and exhibited a rate constant as high as 0.353 min⁻¹, completely converting 4-NP to 4-AP in 9 minutes, almost 1.3 times higher than that of only N-doped CuO (0.268 min⁻¹). In addition, it demonstrated outstanding reusability in five consecutive cycles. Therefore, this study can provide a new way to construct heteroatom-doped catalysts for pollutant treatments and hydrogenation reaction systems.