Bimetallic Fe nanoparticles: Recent advances in synthesis and application in catalytic elimination of environmental pollutants

• Physical and chemical methods to synthesis Fe based bimetallic NPs were reviewed.
• Heavy metals removal involves catalytic replacement reaction.
• The main reactions in the degradation of organic compounds were summerized.
• We concluded the self-inhibition and fouling of bimetallic NPs are the main concern.

As an emerging new class of materials comprising two different metals, bimetallic nanoparticles (NPs) exhibit new functions because of the synergistic rather than merely additive effects of the metals. Compared with monometallic Fe NPs, bimetallic Fe NPs have markedly enhanced physical and chemical properties, including magnetism and reducing ability. However, bimetallic Fe NPs with controlled morphology, size, composition, and structure are often difficult to synthesize. This review summarizes recent advances in the synthesis and environmental application of bimetallic Fe NPs. Different methods of synthesizing bimetallic NPs with different structures, sizes, compositions, and surface properties are summarized. Focus is also given to the catalytic elimination of various environmental pollutants using bimetallic Fe NPs because they have emerged as a promising catalyst for environmental remediation. Their strong reducing ability can be used to remove numerous environmental pollutants (e.g., heavy metals, halogenated organic compounds, nitro and azo compounds, and oxyanions). Reactions between the bimetallic NPs and these pollutants mainly fall into four categories: (1) catalytic replacement reaction for heavy-metal removal, (2) hydrodehalogenation for halogenated hydrocarbons, (3) nitro and azo hydrogenation for nitro and azo compounds, and (4) hydrodeoxygenation for oxyanions. Compared with monometallic Fe NPs, bimetallic Fe NPs have considerable separability and catalytic ability to degrade nonbiodegradable pollutants.

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