Betavoltaic Enhancement Using Defect-Engineered TiO2 Nanotube Arrays through Electrochemical Reduction in Organic Electrolytes

Yang Ma; Na Wang; Jiang Chen; Changsong Chen; Haisheng San; Jige Chen; Zhengdong Cheng

doi:10.1021/acsami.8b05151

Betavoltaic Enhancement Using Defect-Engineered TiO₂ Nanotube Arrays through Electrochemical Reduction in Organic Electrolytes

ACS Appl Mater Interfaces. 2018 Jul 5;10(26):22174-22181. doi: 10.1021/acsami.8b05151. Epub 2018 Jun 19.

Authors

Yang Ma^{1

2}, Na Wang^{1

2}, Jiang Chen^{1

2}, Changsong Chen^{1

2}, Haisheng San^{1

2

3}, Jige Chen³, Zhengdong Cheng^{3

4}

Affiliations

¹ Pen-Tung Sah Institute of Micro-Nano Science and Technology , Xiamen University , Xiamen 361005 , China.
² Shenzhen Research Institute of Xiamen University , Shenzhen 518000 , China.
³ Shenzhen Betary Energy Technologies Co., Ltd. , Shenzhen 518063 , China.
⁴ Artie McFerrin Department of Chemical Engineering , Texas A&M University , College Station , Texas 77843-3122 , United States.

PMID: 29882646
DOI: 10.1021/acsami.8b05151

Abstract

Utilizing high-energy beta particles emitted from radioisotopes for long-lifetime betavoltaic cells is a great challenge due to low energy conversion efficiency. Here, we report a betavoltaic cell fabricated using TiO₂ nanotube arrays (TNTAs) electrochemically reduced in ethylene glycol electrolyte (EGECR-TNTAs) for the enhancement of the betavoltaic effect. The electrochemical reduction of TNTAs using high cathodic bias in organic electrolytes is indeed a facile and effective strategy to induce in situ self-doping of oxygen vacancy (OV) and Ti³⁺ defects. The black EGECR-TNTAs are highly stable with a significantly narrower band gap and higher electrical conductivity as well as UV-vis-NIR light absorption. A 20 mCi of ⁶³Ni betavoltaic cell based on the reduced TNTAs exhibits a maximum ECE of 3.79% with open-circuit voltage of 1.04 V, short-circuit current density of 117.5 nA cm^-2, and a maximum power density of 39.2 nW cm^-2. The betavoltaic enhancement can be attributed to the enhanced charge carrier transport and separation as well as multiple exciton generation of electron-hole pairs due the generation of OV and Ti³⁺ interstitial bands below the conductive band of TiO_2.

Keywords: TiO2; betavoltaic effect; electrochemical reduction; nanotube arrays; organic electrolytes.