•Sn/Pt(100), Sn/Pd(100) and Sn/Pd–Pt(100) were prepared for the nitrate reduction.•Gasous products for the electrochemical NO3RR were analyzed using OLEMS.•Sn/Pd(100) and Sn/Pd-Pt(100) produced N2 ...but not Sn/Pt(100).
We prepared Sn-modified Pt(100), Pd(100) and Pd–Pt(100) single crystal electrodes and investigated the nitrate reduction reaction (NO3RR) activity and the product selectivity for them using online electrochemical mass spectroscopy (OLEMS), also known as differential electrochemical mass spectroscopy (DEMS). OLEMS measurements allowed us to quantify volatile products of N2, N2O and NO and confirm the production of N2 at Sn/Pd(100) but not at Sn/Pt(100). Pd-doping to Pt(100) with a 3 atomic % increased the product selectivity for the NO3RR to N2. These results indicate that the presence of Pd in the (100) surface is the key to produce N2, which seems to be related to the hydrogen adsorption energy to the metal surface. The suppression of hydrogenation of intermediate species at the electrode surface could lead to the production of N2. This work will guide us to understand N2 production mechanism for the NO3RR and develop highly selective electrocatalysts for denitrification.
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Galaxies with stellar masses as high as roughly 10
solar masses have been identified
out to redshifts z of roughly 6, around 1 billion years after the Big Bang. It has been difficult to find massive ...galaxies at even earlier times, as the Balmer break region, which is needed for accurate mass estimates, is redshifted to wavelengths beyond 2.5 μm. Here we make use of the 1-5 μm coverage of the James Webb Space Telescope early release observations to search for intrinsically red galaxies in the first roughly 750 million years of cosmic history. In the survey area, we find six candidate massive galaxies (stellar mass more than 10
solar masses) at 7.4 ≤ z ≤ 9.1, 500-700 Myr after the Big Bang, including one galaxy with a possible stellar mass of roughly 10
solar masses. If verified with spectroscopy, the stellar mass density in massive galaxies would be much higher than anticipated from previous studies on the basis of rest-frame ultraviolet-selected samples.
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