Durable and efficient bi-functional catalyst,that is capable of both oxygen evolution reaction and hydrogen evolution reaction under acidic condition,are highly desired for the commercialization of proton exchange mem...Durable and efficient bi-functional catalyst,that is capable of both oxygen evolution reaction and hydrogen evolution reaction under acidic condition,are highly desired for the commercialization of proton exchange membrane water electrolysis.Herein,we report a robust L-Ru/HfO_(2)heterostructure constructed via confining crystalline Ru nanodomains by HfO_(2)matrix.When assembled with a proton exchange membrane,the bi-functional L-Ru/HfO_(2)catalyst-based electrolyzer presents a voltage of 1.57 and 1.67 V to reach 100 and 300 mA cm^(-2)current density,prevailing most of previously reported Ru-based materials as well as commercial Pt/C||RuO_(2)electrolyzer.It is revealed that the synergistic effect of HfO_(2)modification and small crystalline domain formation significantly alleviates the over-oxidation of Ru.More importantly,this synergistic effect facilitates a dual-site oxide path during the oxygen evolution procedure via optimization of the binding configurations of oxygenated adsorbates.As a result,the Ru active sites maintain the metallic state along with reduced energy barrier for the rate-determining step(^(*)O→^(*)OOH).Both of water adsorption and dissociation(Volmer step)are strengthened,while a moderate hydrogen binding is achieved to accelerate the hydrogen desorption procedure(Tafel step).Consequently,the activity and stability of acidic overall water splitting are simultaneously enhanced.展开更多
Nano-scale Hf/HfO2-based resistive random-access-memory （RRAM） devices were fabricated. The cross-over between top and bottom electrodes of RRAM forms the metal-insulator-metal sandwich structure. The electrical res...Nano-scale Hf/HfO2-based resistive random-access-memory （RRAM） devices were fabricated. The cross-over between top and bottom electrodes of RRAM forms the metal-insulator-metal sandwich structure. The electrical responses of RRAM are studied in detail, including forming process, SET process and RESET process. The correlations between SET voltage and RESET voltage, high resistance state and low resistance state are dis- cussed. The electrical characteristics of RRAM are in a strong relationship with the compliance current in the SET process. The conduction mechanism ofnano-scale Hf/HfO2-based RRAM can be explained by the quantum point contact model.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.22279162,22261142664)Natural Science Fund for Colleges and Universities in Anhui Province(2022AH030057)CAS Project for Young Scientists in Basic Research(No.YSBR-094).
文摘Durable and efficient bi-functional catalyst,that is capable of both oxygen evolution reaction and hydrogen evolution reaction under acidic condition,are highly desired for the commercialization of proton exchange membrane water electrolysis.Herein,we report a robust L-Ru/HfO_(2)heterostructure constructed via confining crystalline Ru nanodomains by HfO_(2)matrix.When assembled with a proton exchange membrane,the bi-functional L-Ru/HfO_(2)catalyst-based electrolyzer presents a voltage of 1.57 and 1.67 V to reach 100 and 300 mA cm^(-2)current density,prevailing most of previously reported Ru-based materials as well as commercial Pt/C||RuO_(2)electrolyzer.It is revealed that the synergistic effect of HfO_(2)modification and small crystalline domain formation significantly alleviates the over-oxidation of Ru.More importantly,this synergistic effect facilitates a dual-site oxide path during the oxygen evolution procedure via optimization of the binding configurations of oxygenated adsorbates.As a result,the Ru active sites maintain the metallic state along with reduced energy barrier for the rate-determining step(^(*)O→^(*)OOH).Both of water adsorption and dissociation(Volmer step)are strengthened,while a moderate hydrogen binding is achieved to accelerate the hydrogen desorption procedure(Tafel step).Consequently,the activity and stability of acidic overall water splitting are simultaneously enhanced.
基金Project supported by the National Natural Science Foundation of China(Nos.11179003,61176095)
文摘Nano-scale Hf/HfO2-based resistive random-access-memory （RRAM） devices were fabricated. The cross-over between top and bottom electrodes of RRAM forms the metal-insulator-metal sandwich structure. The electrical responses of RRAM are studied in detail, including forming process, SET process and RESET process. The correlations between SET voltage and RESET voltage, high resistance state and low resistance state are dis- cussed. The electrical characteristics of RRAM are in a strong relationship with the compliance current in the SET process. The conduction mechanism ofnano-scale Hf/HfO2-based RRAM can be explained by the quantum point contact model.
