In this paper, the application of molecular catalysis for steam reforming of ethanol （SRE） is reviewed. Eight metals （Ni, Co, Cu Pt, Rh, Pd, Ir and Ru） have shown high catalytic activity for SRE. Among them Ni and...In this paper, the application of molecular catalysis for steam reforming of ethanol （SRE） is reviewed. Eight metals （Ni, Co, Cu Pt, Rh, Pd, Ir and Ru） have shown high catalytic activity for SRE. Among them Ni and Rh are very promising because of high d character in the metal bond and low metal-oxygen bonding （vs. metal-carbon）. They can effectively promote C-C bond cleavage in the rate-determining process during SRE. However, Rh is weak in water-gas-shift so that CH4 and CO become the main by-products at low reaction temperatures, while Ni catalysts suffer from rapid deactivation due to coking and sintering. Two low-temperature CO-free catalysts have been developed in our lab, namely Rh-Fe/Ca-Al2O3 and carbonyl-derived Rh-Co/CeO2, in which the presence of iron oxide or Co can promote water-gas-shift reaction and significantly improve the SRE performance. On the other hand, adding 3 wt% CaO to Ni/Al2O3 can greatly improve the catalyst stability because the Ca modification not only increases Ni concentration on the Ni/Ca-Al2O3 surface and 3d valence electron density, but also facilitates the water adsorption and coke gasification via water-gas-shift. The availability of abundant surface OH groups helps the formation and conversion of adsorbed formate intermediate. Hence, ethanol reaction on Ca-Al2O3-supported Ni, Pt, Pd and Rh catalysts are found to follow the formate-intermediated pathway, a new reaction pathway alternative to the traditional acetate-interrnediated pathway.展开更多
Organic polymer solar cells （OSCs） and organic-inorganic hybrid perovskite solar cells （PSCs） have achieved notable progress over the past several years. A central topic in these fields is exploring electronically...Organic polymer solar cells （OSCs） and organic-inorganic hybrid perovskite solar cells （PSCs） have achieved notable progress over the past several years. A central topic in these fields is exploring electronically efficient, stable and effective hole-transporting layer （HTL） materials. The goal is to enhance hole-collection ability, reduce charge recombination, increase built-in voltage, and hence improve the performance as well as the device stability. Transition metal oxides （TMOs） semiconductors such as NiOx, CuOx, CrOx, MoOx, WO3, and V2O5, have been widely used as HTLs in OSCs. These TMOs are naturally adopted into PSC as HTLs and shows their importance. There are similarities, and also differences in applying TMOs in these two types of main solution processed solar cells. This concise review is on the recent developments of transition metal oxide HTL in OSCs and PSCs. The paper starts from the discussion of the cation valence and electronic structure of the transition metal oxide materials, followed by analyzing the structure-property relationships of these HTLs, which we attempt to give a systematic introduction about the influences of their cation valence, electronic structure, work ftmction and film property on device performance.展开更多
基金The funding from the Institute of Chemical and Engineering Sciences,Singapore,to support the project"Alcohol Reforming for Hydrogen Generation"
文摘In this paper, the application of molecular catalysis for steam reforming of ethanol （SRE） is reviewed. Eight metals （Ni, Co, Cu Pt, Rh, Pd, Ir and Ru） have shown high catalytic activity for SRE. Among them Ni and Rh are very promising because of high d character in the metal bond and low metal-oxygen bonding （vs. metal-carbon）. They can effectively promote C-C bond cleavage in the rate-determining process during SRE. However, Rh is weak in water-gas-shift so that CH4 and CO become the main by-products at low reaction temperatures, while Ni catalysts suffer from rapid deactivation due to coking and sintering. Two low-temperature CO-free catalysts have been developed in our lab, namely Rh-Fe/Ca-Al2O3 and carbonyl-derived Rh-Co/CeO2, in which the presence of iron oxide or Co can promote water-gas-shift reaction and significantly improve the SRE performance. On the other hand, adding 3 wt% CaO to Ni/Al2O3 can greatly improve the catalyst stability because the Ca modification not only increases Ni concentration on the Ni/Ca-Al2O3 surface and 3d valence electron density, but also facilitates the water adsorption and coke gasification via water-gas-shift. The availability of abundant surface OH groups helps the formation and conversion of adsorbed formate intermediate. Hence, ethanol reaction on Ca-Al2O3-supported Ni, Pt, Pd and Rh catalysts are found to follow the formate-intermediated pathway, a new reaction pathway alternative to the traditional acetate-interrnediated pathway.
基金supported by the Project of Strategic Importance provided by The Hong Kong Polytechnic University(1-ZE29)the Natural Science Foundation of Hubei Province(2014CFB275)+2 种基金the Special(2016T90724,2014T70735)and General(2015M572187,2013M531737)Postdoctoral Science Foundation of Chinathe National High Technology Research and Development Program(2015AA050601)the National Natural Science Foundation of China(61376013,91433203,11674252)
文摘Organic polymer solar cells （OSCs） and organic-inorganic hybrid perovskite solar cells （PSCs） have achieved notable progress over the past several years. A central topic in these fields is exploring electronically efficient, stable and effective hole-transporting layer （HTL） materials. The goal is to enhance hole-collection ability, reduce charge recombination, increase built-in voltage, and hence improve the performance as well as the device stability. Transition metal oxides （TMOs） semiconductors such as NiOx, CuOx, CrOx, MoOx, WO3, and V2O5, have been widely used as HTLs in OSCs. These TMOs are naturally adopted into PSC as HTLs and shows their importance. There are similarities, and also differences in applying TMOs in these two types of main solution processed solar cells. This concise review is on the recent developments of transition metal oxide HTL in OSCs and PSCs. The paper starts from the discussion of the cation valence and electronic structure of the transition metal oxide materials, followed by analyzing the structure-property relationships of these HTLs, which we attempt to give a systematic introduction about the influences of their cation valence, electronic structure, work ftmction and film property on device performance.
