Engineering Vacancies at the 2D Nanocrystals for Robust Bifunctional Electrocatalysts

Abstract

Hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) through water decomposition are feasible methods to produce green and clean energy. Herein, we report a facile two-step strategy for the preparation of non-noble metal defect-rich nanosheets by an electrochemical process at room temperature. First-principle calculations are used to study the bifunctional catalytic reaction mechanism of defect engineering in transition-metal dichalcogenides (TMDs); from the first-principle calculations, we predicted that the rich S vacancies on the nanosheet promoted electron transfer and reduced the energy barrier of electrocatalysis. As a substantiation, we conducted HER/ OER electrochemical characterizations and found that the defectrich atomic-thick tantalum sulfide is a kind of dual-function electrocatalyst with enhanced comprehensive properties of Tafel slope (39 mV/dec for HER, 38 mV/dec for OER) and low overpotential (0.099 V for HER, 0.153 V for OER) in acidic and alkaline environments, respectively. Likewise, the defect-rich catalysts exhibit high stability in acidic and alkaline solutions, which have potential applications as electrocatalysts for the large-scale production of hydrogen and oxygen.

Cu intercalation and defect engineering realize an atomic-scale hydrogen spillover effect in NbS2 to boost acidic hydrogen evolution

“…After the S vacancies were induced, the Nb 4+ peaks moved back toward higher binding energies (203.18 and 206.08 eV) in Cu 0.4 NbS 2− δ . 44 For S 2p spectra in Fig. 2b, the S 2p 3/2 and 2p 1/2 peaks shifted to higher binding energies after Cu intercalation (from 161.08 and 162.28 eV in NbS 2 to 161.88 and 160.68 eV in Cu 0.4 NbS 2 ), and they further moved to a higher range in Cu 0.4 NbS 2− δ (161.28 and 162.58 eV) after the partial removal of S atoms, implying the re-distribution of electrons after the chemical intercalation and defects induced in this system.…”

A review of modulation strategies for improving the catalytic performance of transition metal sulfide self-supported electrodes for the hydrogen evolution reaction

“…Theoretical calculations demonstrated that the S vacancies in TaS x NSs could facilitate the electron transfer between H and TaS x , thus lowering the overpotential and promoting hydrogen generation. 102…”