Highly active and low-cost catalysts for electrochemical reactions such as the hydrogen evolution reaction （HER） are crucial for the development of efficient energy conversion and storage technologies. Theoretical s...Highly active and low-cost catalysts for electrochemical reactions such as the hydrogen evolution reaction （HER） are crucial for the development of efficient energy conversion and storage technologies. Theoretical simulations have been instrumental in revealing the correlations between the electronic structure of materials and their catalytic activity, and guide the prediction and development of improved catalysts. However, difficulties in accurately engineering the desired atomic sites lead to challenges in making direct comparisons between experi- mental and theoretical results. In MoS2, the Mo-edge has been demonstrated to be active for HER whereas the S-edge is inert. Using a computational descriptor- based approach, we predict that by incorporating transition metal atoms （Fe, Co, Ni, or Cu） the S-edge site should also become HER active. Vertically standing, edge-terminated MoS2 nanofilms provide a well-defined model system for verifying these predictions. The transition metal doped MoS2 nanofilms show an increase in exchange current densities by at least two-fold, in agreement with the theoretical calculations. This work opens up further opportunities for improving electrochemical catalysts by incorporating promoters into particular atomic sites, and for using well-defined systems in order to understand the origin of the promotion effects.展开更多
Well aligned nanotubes with diameter of 30—50 nm have been synthesized on a porous alumina template by microwave plasma enhanced chemical vapor deposition (MW PECVD). By this means, the control over either diameter o...Well aligned nanotubes with diameter of 30—50 nm have been synthesized on a porous alumina template by microwave plasma enhanced chemical vapor deposition (MW PECVD). By this means, the control over either diameter or length of the nanotubes could be realized. The hollow structure and vertically aligned features have been verified by scanning electron and transmission electron microscopic images. In comparison with the reported fabrication methods, lower synthesis temperature (below 520 ℃) and simpler process (no negative dc bias applied) have been achieved, which could be of great importance for both theoretical research and pratical applications.展开更多
文摘Highly active and low-cost catalysts for electrochemical reactions such as the hydrogen evolution reaction （HER） are crucial for the development of efficient energy conversion and storage technologies. Theoretical simulations have been instrumental in revealing the correlations between the electronic structure of materials and their catalytic activity, and guide the prediction and development of improved catalysts. However, difficulties in accurately engineering the desired atomic sites lead to challenges in making direct comparisons between experi- mental and theoretical results. In MoS2, the Mo-edge has been demonstrated to be active for HER whereas the S-edge is inert. Using a computational descriptor- based approach, we predict that by incorporating transition metal atoms （Fe, Co, Ni, or Cu） the S-edge site should also become HER active. Vertically standing, edge-terminated MoS2 nanofilms provide a well-defined model system for verifying these predictions. The transition metal doped MoS2 nanofilms show an increase in exchange current densities by at least two-fold, in agreement with the theoretical calculations. This work opens up further opportunities for improving electrochemical catalysts by incorporating promoters into particular atomic sites, and for using well-defined systems in order to understand the origin of the promotion effects.
文摘Well aligned nanotubes with diameter of 30—50 nm have been synthesized on a porous alumina template by microwave plasma enhanced chemical vapor deposition (MW PECVD). By this means, the control over either diameter or length of the nanotubes could be realized. The hollow structure and vertically aligned features have been verified by scanning electron and transmission electron microscopic images. In comparison with the reported fabrication methods, lower synthesis temperature (below 520 ℃) and simpler process (no negative dc bias applied) have been achieved, which could be of great importance for both theoretical research and pratical applications.
