Electrochemical sensors for ultra trace determination of radionuclides in environmental and nuclear samples

Abstract Electrochemical sensing has emerged as a powerful analytical approach for the ultra trace determination and speciation of radionuclides across environmental systems and nuclear fuel cycle process streams. This review synthesizes recent advances in electrode engineering, surface modification strategies, and redox mechanistic understanding that have collectively transformed electroanalytical radiochemistry. Fundamental techniques such as adsorptive stripping voltammetry and ion selective potentiometry are discussed in the context of their ability to deliver picomolar level detection while providing direct electronic signatures of oxidation states, a capability not readily achievable with spectrometric methods. Progress in replacing mercury based systems with environmentally benign solid state platforms, including bismuth film, boron doped diamond, screen printed electrodes, and nanomaterial modified carbon architectures, has significantly enhanced sensitivity, stability, and field deployability. Equally important are advances in selective interfaces such as ion imprinted polymers, molecularly imprinted polymers, metal organic frameworks, and Prussian Blue analogues, which mitigate matrix interferences in seawater, groundwater, biological samples, and high level liquid waste. This review comprehensively examines the electrochemical behaviors of uranium, plutonium, neptunium, americium, technetium, strontium, and cesium, highlighting the interplay between electrode materials, complexation chemistry, radiation induced perturbations, and kinetic limitations. In addition, operational considerations including memory effects, waste minimization, radiation damage, and comparative performance with inductively coupled plasma mass spectrometry are critically evaluated. Collectively, these developments demonstrate that modern electrochemical sensors offer a versatile, low cost, and highly informative complement to traditional radiometric and mass spectrometric techniques, particularly for applications requiring rapid on site screening and oxidation state resolved monitoring in complex nuclear environments.