Amorphous Ni–Fe–B bimetallic borides: boron-mediated synergy for ultrafast and stable 4-nitrophenol reduction

Abstract

The efficient reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) has garnered significant interest in the fields of environmental remediation and chemical manufacturing. However, conventional catalytic reduction methods encounter challenges such as insufficient catalyst activity, poor stability, and high costs. Nickel–iron bimetallic systems offer promise due to their synergistic effects, and recent studies have shown that boron incorporation (Ni–Fe–B) further enhances activity through electronic modulation and improved charge transfer. Despite these advantages, the potential of Ni–Fe–B for 4-NP reduction remains largely unexplored. In this study, a series of Ni–Fe–B catalysts with tunable Ni/Fe ratios were synthesized via ultrasound-assisted reduction and evaluated for the catalytic reduction of 4-NP at room temperature. By systematically adjusting the Ni/Fe molar ratio, we optimized the morphology and electronic structure of the catalysts, leading to significantly enhanced catalytic performance. Notably, this study pioneers the application of Ni–Fe–B catalysts for 4-NP reduction. Remarkably, the Ni₃Fe₁–B sample demonstrated exceptional activity, achieving complete 4-NP conversion within just 3 minutes, surpassing the performance of monometallic borides (Ni–B or Fe–B). This enhancement is attributed to the strong synergistic effect between Ni and Fe, where electron redistribution facilitated by boron incorporation promotes hydrogenation kinetics. Furthermore, Ni₃Fe₁–B exhibited excellent cycling stability, maintaining high activity over multiple runs without significant degradation, which is crucial for practical applications. These findings not only establish Ni–Fe–B as a highly efficient catalyst system for 4-NP reduction but also provide fundamental insights into the design of bimetallic boride materials for sustainable chemical transformations.