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[Display omitted] • Interaction of beta particles with ECSs was simulated using Monte Carlo method. • ZrO 2 @Ar-TNRAs structure was used as the beta-anode of EBCs. • Photoelectrochemical performance was used to optimize the ECSs. • TiO 2 /ZrO 2 heterojunction with type-I band alignment can enhance the electrochemical redox reaction. Direct energy conversion from beta radiation to electricity using betavoltaic effect is a promising energy conversion technology for a long-time and highly efficient power supply. This work presents an electrochemical betavoltaic cell (EBC), consisting of a beta-anode with TiO 2 nanorod arrays (TNRAs) modified with ZrO 2 nanoparticles, a polyiodide (I −/ I 3 −) electrolyte, and a 63Ni/Ni counter electrode. Free-standing TNRAs structures were fabricated using hydrothermal method and post-annealed in Ar atmosphere to enable a rutile TiO 2 material with excellent electrochemical performance. Monte Carlo (MC) method was used to determine the optimum length (∼2.5 μm) of the TiO 2 nanorods. Investigation on ultraviolet photoelectrochemical performance of EBCs was used to evaluate and optimize the content of ZrO 2 (thickness of ∼10 nm) modified on the TNRAs. The EBCs demonstrated an energy conversion efficiency of 9.27% with an open-circuit voltage of 0.276 V and short-circuit current density of 1.041 μA·cm−2 when using a 10 mCi 63Ni source. The enhanced performance can be ascribed to the three-dimensional ZrO 2 /TiO 2 heterojunction with a large specific area in favor of the interface carrier transfer as well as the suppression of carrier recombination through the type-I band barrier, effectively promoting the electrochemical redox reaction. [ABSTRACT FROM AUTHOR]

Highly efficient direct energy conversion utilizing the betavoltaic effect is a promising alternative for developing of maintenance-free and long-life self-generating power cells. This work demonstrates a betavoltaic-powered electrochemical cell (BPEC) using free-standing TiO 2 nanotube arrays (TNTAs) incorporated with single-wall carbon nanotubes (SWCNTs) as the beta anode, a polyiodide (I − / I 3 − ) solution as the electrolyte, and a radioisotope 63Ni/Ni sheet as the cathode as well as the irradiation source. Freestanding TNTAs were fabricated using electrochemical anodization. Monte Carlo simulations were used to investigate the interaction of the incident beta particles with the TNTAs structure. Experimentally, the photoelectrochemical characteristics were used to optimize the structural design of the BPECs. The optimum BPEC exhibited an energy conversion efficiency of 8.74% with an open circuit voltage of 0.26 V and a short circuit current density of 0.87 μA/cm2. The enhanced betavoltaic effect is attributed to the highly efficient separation and transport of beta-generated carriers through the enhanced beta-electrochemical redox reactions in the 3-D TiO 2 /liquid heterojunction as well as the extensive SWCNTs conductive network. [Display omitted] • Monte Carlo simulation is used to investigate the interaction of beta particles with energy conversion structures. • TNTAs incorporated with SWCNTs were used as the beta-anode of BPECs. • Photoelectrochemical performance is used to evaluate and optimize the structure design of BPECs. • Beta-excited electrochemical reaction is enhanced by the 3-D TiO 2 /liquid heterojunction and SWCNTs conductive network. [ABSTRACT FROM AUTHOR]