The widespread use of proton exchange membrane water electrolysis requires the development of more efficient electrocatalysts containing reduced amounts of expensive iridium for the oxygen evolution reaction (OER). Here we present the identification of 6H-phase SrIrO3 perovskite (6H-SrIrO3) as a highly active electrocatalyst with good structural and catalytic stability for OER in acid. 6H-SrIrO3 contains 27.1 wt% less iridium than IrO2, but its iridium mass activity is about 7 times higher than IrO2, a benchmark electrocatalyst for the acidic OER. 6H-SrIrO3 is the most active catalytic material for OER among the iridium-based oxides reported recently, based on its highest iridium mass activity. Theoretical calculations indicate that the existence of face-sharing octahedral dimers is mainly responsible for the superior activity of 6H-SrIrO3 thanks to the weakened surface Ir-O binding that facilitates the potential-determining step involved in the OER (i.e., O* + H2O → HOO* + H+ + e¯).

between electrical and chemical energy to store off-peak electricity produced from these resources. The opportunities relate to the fact that electrocatalytic reactions can be employed to convert these excess and off-peak electricity into chemical bonds in molecules. A fascinating prospect is the utilization of renewable electricity for the conversion of abundant resources such as H 2 O, N 2 , and CO 2 into synthetic fuels such as hydrogen, ammonia, hydrocarbons, and alcohols under ambient conditions (Figure 1). Through the reverse processes, clean electricity can be generated from the products, for example, via hydrogen-, ammonia-, or alcohol-powered fuel cells, ultimately resulting in a closed water cycle, nitrogen cycle, or carbon cycle. Hydrogen production via electrocatalytic water splitting, which may enable the hydrogen economy, is a notable example to these. [2] At present, the annual hydrogen production worldwide exceeds more than 65 million tons, mainly for industrial uses such as petroleum refining and ammonia synthesis. Unfortunately, most of the hydrogen is produced from fossil fuels through steam methane reforming and coal gasification and is accompanied by large emission of the greenhouse gas CO 2. Producing hydrogen from water using renewable electricity provides a green and sustainable pathway for future hydrogen energy cycle. In a similar vein, renewable energy-powered electrocatalysis of CO 2 and N 2 reduction produces high-value fuels or fine chemicals such as formic acid (HCOOH), carbon monoxide (CO), methanol (CH 3 OH), and ammonia (NH 3) under ambient conditions. [3] The use of these renewable fuels (e.g., hydrogen and alcohols), instead of petroleum-based fuels, for transportation applications is receiving unprecedented attention because the former are more environmentally friendly and sustainable. Fuel cell technologies based on these fuels can reliably supply electrical energy and are, thus, highly desired for running emerging electric vehicles. [4] To realize the water cycle, carbon cycle, and nitrogen cycle described above, the central reactions are the hydrogen evolution reaction (HER), the CO 2 reduction reaction (CO 2 RR), and the nitrogen reduction reaction (NRR), as well as the oxygenrelated reactions, including the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR), which are important half reactions in electrolyzers and fuel cells, respectively. In these energy conversion processes, electrocatalysts are indispensable. The desired electrocatalysts should both Electrocatalysis is at the center of many sustainable energy conversion technologies that are being developed to reduce the dependence on fossil fuels. The past decade has witnessed significant progresses in the exploitation of advanced electrocatalysts for diverse electrochemical reactions involved in electrolyzers and fuel cells, such as the hydrogen evolution reaction (HER), the oxygen reduction reaction (ORR), the CO 2 reduction reaction (CO 2 RR), the nitrogen reduction reaction (NRR), and the oxyge...

Heteroatoms of Al and Ti are effectively introduced into the framework of ordered mesoporous silica materials (designated as MAS-7 and MTS-9, respectively) in strong acidic media (pH < 0) by a two-step procedure. MAS-7 shows high catalytic activities for the cracking of both small (cumene) and bulky (1,3,5-triisopropylbenzene) molecules because it combines the advantages of both zeolites (strong acidity) and mesoporous materials (large pores). In contrast, Al-SBA-15 samples prepared from both "post-synthesis" and "direct synthesis" present much lower catalytic activities than MAS-7. Furthermore, MTS-9 exhibits very high catalytic activity in phenol hydroxylation by H 2 O 2 , giving the phenol conversion of 26%, comparable to TS-1.

No abstract

An effective boronization strategy is presented for transforming metal sheets into highly intrinsic active, stable and corrosion-resistant oxygen evolution electrodes.

Understanding of catalytic trends is an important prerequisite for providing rational guidance toward the prediction of advanced catalysts as well as the development of original materials design principles. A combined theoretical and experimental study that reveals the periodic trends in electrocatalytic activity for the hydrogen evolution reaction (HER) from Group IV B to Group VIII metal diborides is reported here. Theoretical results demonstrate a general linear relationship between the catalytic activity and d‐band center of metal diboride, meaning that the latter can serve as a descriptor of activity. And theoretical results also predict ruthenium diboride as the most competitive, nonplatinum candidate among metal diborides for HER because this material has a suitable d‐band center and a high density of efficient active sites. Furthermore, the experimental results validate the theoretical activity trends and identify ruthenium diboride as an efficient, pH‐universal electrocatalyst with Pt‐like activity for HER under both acidic and alkaline media.

The fundamental understanding and rational manipulation of catalytic site preference at extended solid surfaces is crucial in the search for advanced catalysts.Herein we find that the Ru top sites at metallic ruthenium surface have efficient Ptlike activity for the hydrogen evolution reaction (HER), but they are subordinate to their adjacent, less active Ru 3 -hollow sites due to the stronger hydrogen-binding ability of the latter. We also present an interstitial incorporation strategy for the promotion of the Ru top sites from subordinate to dominant character,w hile maintaining Pt-like catalytic activity.O ur combined theoretical and experimental studies further identify intermetallic RuSi as ah ighly active,n on-Pt material for catalyzing the HER, because of its suitable electronic structure governed by ag ood balance of ligand and strain effects.

The effects of macromolecular crowding on protein stability and folding kinetics have been studied using the recently developed 15N spin relaxation dispersion technique. By applying this method to a redesigned apocytochrome b562, the kinetics and thermodynamics of the protein folding processes in both the presence and the absence of crowding agents have been characterized. The result indicates that, even under the mild crowded environments (in the presence of 85 mg/mL of PEG 20K), the folding rate of the protein can speed up significantly while the unfolded rate remains unchanged within experimental error.