Searching for highly efficient and durable electrocatalysts for the hydrogen evolution reaction (HER) that function effectively at all pHs is of great interest to the scientific community, however it is still a grand challenge, because the HER kinetics of Pt in alkaline solutions are approximately two to three orders of magnitude lower than that in acidic solution. Herein, a new class of wrinkled, ultrathin Rh2P nanosheets for enhancing HER catalysis at all pHs is reported. They exhibit a small overpotential of 18.3 mV at 10 mA cm−2, low Tafel slope of 61.5 mV dec−1, and good durability in alkaline media, much better than the commercial Pt/C catalyst. Density functional theory calculations reveal that the active open‐shell effect from the P‐3p band not only promotes Rh‐4d for increased proton–electron charge exchange but also provides excellent p–p overlapping to locate the O‐related species as distributary center, which can benefit the HER process in alkaline media. It is also demonstrated that the present wrinkled, ultrathin Rh2P nanosheets are highly efficient and durable electrocatalysts toward HER in both acid and neutral electrolytes. The present work opens a new material design for ultrathin 2D metal phosphide nanostructures for the purpose of boosting HER performance at all pHs.
Despite intense research in past decades, the development of high‐performance bifunctional catalysts for direct ethylene glycol or glycerol oxidation reaction (EGOR or GOR) and oxygen reduction reaction (ORR) remains a grand challenge in realizing fuel‐cell technologies for portable electronic devices and fuel‐cell vehicle applications. Here, a general method is reported for controllable synthesis of a class of ultrathin multimetallic PtPdM (M = Ni, Fe, Co) nanosheets (NSs) with a thickness of only 1.4 nm by coreduction of metal precursors in the presence of CO and oleylamine. With the optimized composition and components, ultrathin Pt32Pd48Ni20 NSs exhibit the highest electrocatalytic activity for EGOR, GOR, and ORR among all different ultrathin PtPdM NSs, ultrathin PtPd NSs, and the commercial catalysts. The mass activities of ultrathin Pt32Pd48Ni20 NSs for EGOR, GOR, and ORR are 7.7, 5.4, and 7.7 times higher respectively than a commercial catalyst, and they are the most efficient nanocatalysts ever reported for EGOR/GOR. The ultrathin PtPdNi NSs are also very stable for EGOR/GOR/ORR. It is further demonstrated that these ultrathin multimetallic NSs can be readily generalized to other sensor‐related electrocatalysis system such as high‐sensitivity electrochemical detection of H2O2.
Designing highly efficient interface catalysts with new interface-enhancing mechanisms for the oxygen reduction reaction (ORR) in acid solution still remains a significant challenge. Here, we report a class of stable PtFe-Fe 2 C Janus-like nanoparticle (NP) interface catalysts with an unrevealed barrier-free interface electron-transfer property that greatly boosts ORR catalytic activity and stability. The PtFe-Fe 2 C Janus-like NPs showed much higher catalytic activity for ORR than either PtFe or Fe 2 C NPs in both acidic and alkaline electrolytes. Density functional theory simulations revealed that a barrier-free interface electron transfer on the interface of PtFe-Fe 2 C Janus-like NPs is the main factor in enhancing ORR activity. This interface electron-transfer property makes them the most active for ORR among all reported PtFe-based nanocatalysts. We further demonstrate that this barrier-free interface electron-transfer property can be readily generalized to other systems, such as the hydrogen evolution reaction and H 2 O 2 reduction electrocatalysis, to achieve better electrocatalytic enhancement.
It is well recognized that improving nitrogen use efficiency (NUE) can directly reduce nitrous oxide (N 2 O) emission in cropland and indirectly reduce carbon dioxide (CO 2 ) release from nitrogen (N) production, while such a reduction has not been well quantified in China. We estimated the greenhouse gas (GHG; N 2 O and CO 2 ) mitigation potential (MP) from Chinese cropland and its regional distribution by quantifying NUE and determining the amount of over-applied synthetic N under various scenarios of NUE. We estimated that synthetic NUE in the late 1990s was 31 AE 11% (mean AE SD) for rice, 33 AE 13% for wheat, and 31 AE 11% for maize cultivation. Improving NUE to 50% could cut 6.6 Tg of synthetic N use per year, accounting for 41% of the total used. As a result of this reduction, the direct N 2 O emission from croplands together with CO 2 emission from the industrial production and transport of synthetic N could be reduced by 39%, equivalent to 60 Tg CO 2 yr À1 . The MP was probably underestimated because organic N supply was not taken into account when estimating NUE. It was concluded that improving N management can greatly reduce GHG (N 2 O and CO 2 ) emissions in Chinese croplands, and mitigation in the Jiangsu, Henan, Shandong, Sichuan, Hubei, Anhui, and Hebei provinces should be given priority.
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