Abstract
Despite significant progress in MBene research, achieving perfect layered structures and high purity under different etching conditions remains challenging. Additionally, their potential for heavy metal ion detection in electrochemical applications is underexplored. The synthesis of MBenes, particularly MoB, involves removing Al precursor MoAlB. Recent advancements focus on high-temperature solid-state etching using Lewis bases or chemical wet etching, with wet etching proving more economical, milder, and higher purity products. This study compares various non-fluoride etchants' effects. Ammonium persulfate (APS) achieved a significant etching rate of ~71% for Al, resulting in restacked accordion-like multilayered MBene. However, high temperatures led to stable, insoluble AlxO, reducing product purity. CuCl₂ etching yielded a lower rate of ~54%, producing flake structures with copper impurities. Acid etching resulted in a perfect layered structure but lower purity, while alkali etching provided similar etching rates to APS with the highest purity. Complete Al removal at elevated temperatures caused the loss of the layered structure. Maintaining a small amount of Al during hydrothermal etching supports the layered structure, and subsequent room-temperature etching produces fluffy open-layered MBene MoB (OL-MBene).Electrochemical studies revealed that OL-MBene-modified GCE exhibited excellent performance in detecting Cd²⁺, Pb²⁺, Cu²⁺, and Hg²⁺ ions individually and simultaneously, with high sensitivity and selectivity. Notably, the sensor exhibited superior performance for Cu²⁺ and Pb²⁺ ions. The varying adsorption energies of these ions explain the differences in sensitivity and selectivity, and Pb²⁺ demonstrated the highest sensitivity due to its lowest adsorption energy on the MBene surface. Competitive adsorption studies indicated that Pb²⁺ competes with Hg²⁺ for adsorption sites while having minimal impact on Cd²⁺ and Cu²⁺ adsorption. This research advances our understanding of MBene synthesis and characterization, introducing a new avenue for leveraging MBenes in sensitive and selective electrochemical sensors for environmental monitoring. Figure 1
Published Version
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