Photoredox-Promoted Co-Production of Dihydroisoquinoline and H2 O2 over Defective Zn3 In2 S6.

One of the most sustainable and promising approaches for hydrogen peroxide (H2 O2 ) production in a low-cost and environment-friendly way is photosynthesis, which, however, suffers from poor carrier utilization and low H2 O2 productivity. The addition of proton donors such as isopropanol or ethanol can increase H2 O2 production, which, unfortunately, will inevitably elevate the entire cost while wasting the oxidizing power of holes (h+ ). Herein, the tetrahydroisoquinolines (THIQs) is employed as a distinctive proton donor for the thermodynamically feasible and selective semi-dehydrogenation reaction to highly valuable dihydroisoquinolines (DHIQs), and meanwhile, to couple with and promote H2 O2 generation in one photoredox reaction under the photocatalysis by dual-functional Zn3 In2 S6 photocatalyst. Surprisingly, the suitably defective Zn3 In2 S6 offers an excellent and near-stoichiometric co-production performance of H2 O2 and DHIQs at unprecedentedly high rates of 66.4 and 62.1 mmol h-1 g-1 under visible light (λ ≥ 400 nm), respectively, which outperforms all the previously available reports even though sacrificial agents were employed in those reports. Additionally, photocatalytic redox reaction mechanism demonstrates that H2 O2 can be generated through multiple pathways, highlighting the synergistic effect among ROS (·O2 - and 1 O2 ), h+ and proton donor, which has been ignored in previous studies.

MnO2 Electrocatalysts Coordinating Alcohol Oxidation for Ultra-Durable Hydrogen and Chemical Productions in Acidic Solutions.

Electrocatalytic hydrogen production under acidic conditions is of great importance for industrialization in comparison to that in alkaline media, which, unfortunately, still remains challenging due to the lack of earth-abundant, cost-effective and highly active anodic electrocatalysts that can be used durably under strongly acidic conditions. Here we report an unexpected finding that manganese oxide, a kind of common non-noble catalysts easily soluble in acidic solutions, can be applied as a highly efficient and extremely durable anodic electrocatalyst for hydrogen production from an acidic aqueous solution of alcohols. Particularly in a glycerol solution, a potential of as low as 1.36 V (vs. RHE) is needed at 10 mA cm-2 , which is 270 mV lower than that of oxygen evolution reaction (OER), to oxidize glycerol into value-added chemicals such as formic acid, without oxygen production. To our surprise, the manganese oxide exhibits extremely high stability for electrocatalytic hydrogen production in coupling with glycerol oxidation for longer than 865 hours compared to shorter than 10 h for OER. Moreover, the effect of the addition of glycerol on the electrochemical durability has been probed via in situ Raman spectroscopic analysis and density functional theory (DFT) calculations. This work demonstrates that acid-unstable metal oxide electrocatalysts can be used robustly in acidic media under the presence of certain substances for electrochemical purposes, such as hydrogen production.

Electrocatalytic Hydrogen Production Trilogy.

H2 production via water electrolysis is of great significance in clean energy production, which, however, suffers from the sluggish kinetics of the anodic oxygen evolution reaction (OER). Moreover, the anode product, O2 , which is of rather low value, may lead to dangerous explosions and the generation of membrane-degrading reactive oxygen species. Herein, to address these issues of electrocatalytic H2 production, we summarize the most recent advances in three stages based on the benefit increments and various electron donation routes, which are: 1) electron donation by traditional OER: developing efficient catalysts for water oxidation to promote H2 production; 2) electron donation by the oxidation of sacrificial agents: using sacrificial agents to assist H2 production; 3) electron donation by electrosynthesis reaction: achieving electrosynthesis in parallel with cathodic H2 production. Present challenges and related prospects will also be discussed, hopefully to benefit the further progress of electrocatalytic H2 generation.

Formic Acid Electro-Synthesis by Concurrent Cathodic CO2 Reduction and Anodic CH3 OH Oxidation.

The electrochemical conversion of carbon dioxide into energy-carrying compounds or value-added chemicals is of great significance for diminishing the greenhouse effect and the efficient utilization of carbon-dioxide emissions, but it suffers from the kinetically sluggish anodic oxygen evolution reaction (OER) and its less value-added production of O2 . We report a general strategy for efficient formic-acid synthesis by a concurrent cathodic CO2 reduction and anodic partial methanol-oxidation reaction (MOR) using mesoporous SnO2 grown on carbon cloth (mSnO2 /CC) and CuO nanosheets grown on copper foam (CuONS/CF) as cathodic and anodic catalysts, respectively. Anodic CuONS/CF enables an extremely lowered potential of 1.47 V vs. RHE (100 mA cm-2 ), featuring a significantly enhanced electro-activity in comparison to the OER. The cathodic mSnO2 /CC shows a rather high Faraday efficiency of 81 % at 0.7 V vs. RHE for formic-acid production from CO2 . The established electrolyzer equipped with CuONS/CF at the anode and mSnO2 /CC at the cathode requires a considerably low cell voltage of 0.93 V at 10 mA cm-2 for formic-acid production at both sides.

Sleep heart rate variability assists the automatic prediction of long-term cardiovascular outcomes.

OBJECTIVE: We aimed to investigate the association between sleep HRV and long-term cardiovascular disease (CVD) outcomes, and further explore whether HRV features can assist the automatic CVD prediction. METHODS: We retrospectively analyzed polysomnography (PSG) data obtained from 2111 participants in the Sleep Heart Health Study, who were followed up for a median of 11.8 years after PSG acquisition. During follow-up, 1252 participants suffered CVD events (CVD group) and 859 participants remained CVD-free (non-CVD group). HRV measures, derived from time-domain and frequency-domain, were calculated. Regression models were created to determine the independent predictor for long-term CVD outcomes, and to explore the association between HRV and CVD latency. Furthermore, based on HRV and other clinical features, a model was trained to automatically predict CVD outcomes using the eXtreme Gradient Boosting algorithm. RESULTS: Compared with the non-CVD group, decreased HRV during sleep was found in the CVD group. HRV, particularly its component of high frequency (HF), was demonstrated to be independent predictor of CVD outcomes. Moreover, normalized HF was positively correlated with CVD latency. The proposed prediction model achieved a total accuracy of 75.3%, in which sleep HRV features served as a supplement to the well-recognized CVD risk factors, such as aging, adiposity and sleep disorders. CONCLUSIONS: Association between sleep HRV and long-term CVD outcomes was demonstrated here, suggesting that altered HRV during sleep might occur many years prior to the onset of CVD. Machine learning models, combining sleep HRV and other clinical characteristics, should be promising in the early prediction of CVD outcomes.

Nickel-molybdenum nitride nanoplate electrocatalysts for concurrent electrolytic hydrogen and formate productions.

Hydrogen production by electrocatalytic water splitting is an efficient and economical technology, however, is severely impeded by the kinetic-sluggish and low value-added anodic oxygen evolution reaction. Here we report the nickel-molybdenum-nitride nanoplates loaded on carbon fiber cloth (Ni-Mo-N/CFC), for the concurrent electrolytic productions of high-purity hydrogen at the cathode and value-added formate at the anode in low-cost alkaline glycerol solutions. Especially, when equipped with Ni-Mo-N/CFC at both anode and cathode, the established electrolyzer requires as low as 1.36 V of cell voltage to achieve 10 mA cm-2, which is 260 mV lower than that in alkaline aqueous solution. Moreover, high Faraday efficiencies of 99.7% for H2 evolution and 95.0% for formate production have been obtained. Based on the excellent electrochemical performances of Ni-Mo-N/CFC, electrolytic H2 and formate productions from the alkaline glycerol solutions are an energy-efficient and promising technology for the renewable and clean energy supply in the future.

Metal-Organic Framework Nanosheet Electrocatalysts for Efficient H2 Production from Methanol Solution: Methanol-Assisted Water Splitting or Methanol Reforming?

Hydrogen (H2) is presently one of the most promising clean and renewable energy sources, but the conventional hydrogen production by electrochemical water-splitting, though of great potential and extensively studied, is seriously obstructed especially by the anodic oxygen evolution reaction because of its sluggish kinetics. Herein, we report the efficient hydrogen production from methanol solution using facile-synthesized ultrathin 2D bi-metal-organic framework nanosheets (UMOFNs) as a precious metal-free anodic catalyst. The prepared UMOFNs showed a much lowered anodic potential of 1.365 (V vs reversible hydrogen electrode) at 10 mA cm-2, which was markedly 232 mV lower than that in conventional water splitting, and moreover, the average turnover frequency reached 19.62 s-1. Benefiting from nearly 100% Faraday efficiency of H2 production on the counter graphite carbon electrodes without additional electrocatalysts, high-purity hydrogen was produced with enhanced efficiency. More importantly, the anodic electro-reaction mechanism has been evidenced experimentally: the electrocatalytic hydrogen production from the methanol solution is a methanol-assisted water splitting, rather than a methanol-reforming process as claimed in a number of literature studies, in which methanol is oxidized as a sacrificing agent in place of water oxidization in pure water.