Search

Hydrogen is an ideal energy carrier in future applications due to clean byproducts and high efficiency. However, many challenges remain in the application of hydrogen, including hydrogen production, delivery, storage and conversion. In terms of hydrogen storage, two compression modes (mechanical and non-mechanical compressors) are generally used to increase volume density in which mechanical compressors with several classifications including reciprocating piston compressors, hydrogen diaphragm compressors and ionic liquid compressors produce significant noise and vibration and are expensive and inefficient. Alternatively, non-mechanical compressors are faced with issues involving large-volume requirements, slow reaction kinetics and the need for special thermal control systems, all of which limit large-scale development. As a result, modular, safe, inexpensive and efficient methods for hydrogen storage are urgently needed. And because electrochemical hydrogen compressors (EHCs) are modular, highly efficient and possess hydrogen purification functions with no moving parts, they are becoming increasingly prominent. Based on all of this and for the first time, this review will provide an overview of various hydrogen compression technologies and discuss corresponding structures, principles, advantages and limitations. This review will also comprehensively present the recent progress and existing issues of EHCs and future hydrogen compression techniques as well as corresponding containment membranes, catalysts, gas diffusion layers and flow fields. Furthermore, engineering perspectives are discussed to further enhance the performance of EHCs in terms of the thermal management, water management and the testing protocol of EHC stacks. Overall, the deeper understanding of potential relationships between performance and component design in EHCs as presented in this review can guide the future development of anticipated EHCs.Graphic Abstract

Background Currently there is no guideline based on preoperative clinical parameters for assessing the prognosis of the adjunctive surgery for drug-resistant tuberculosis. Methods We retrospectively analyzed 138 patients who had undergone surgical resection as a treatment for drug- resistant tuberculosis after 24 months. Four clinical parameters on lesion type, treatment history, body physiological status, and surgery approach were evaluated. Categorical preoperative clinical parameters were analyzed by ordinal logistic regression model when considering postoperative complications as outcomes ordered in terms of severity. Statistically significant parameters were then combined in a single classification system for predicting the outcomes of the adjunctive surgery. Findings Diffused, progressive bilateral lesions, or active/progressive extra pulmonary tuberculosis (L3), and history of less than 2 months treatment before surgery (T3) were the strongest predicative parameters for postoperative complications and for surgery failure. Classification systems based on the four parameters were found to have a statistically significant effect on postoperative complications and postoperative efficacy. 24- month follow up indicated a high cure rate (above 95.5%) among patients without T3, L3, or severe physiological complications (B3). Interpretation A classification system based on objective clinical parameters showed predicative value for the prognosis of the adjunctive surgery and could guide management of drug-resistant Tuberculosis.

Large-scale and accurate monitoring soil salinization is essential for controlling soil degradation and sustainable agricultural development. The agricultural irrigation area of the Manas River Basin in the arid area of Northwest China was selected as the test area. The soil salinization monitoring model based on spectral index group was constructed by comparing the accuracy of PCR, PLSR and MLR models using the transformation of multi-spectral index group and index screening. The results showed that there was a certain correlation between the 28 spectral index groups, with a maximum correlation coefficient -0.3689 between the original spectral group and the soil salt content was B10 band. After the transformation of original data for the logarithm Ln(R), exponential eR and square root R1/2 respectively, the correlation between each index and soil salinity was significantly improved, with the maximum correlation coefficient was up to -0.7564 of R1/2. The salt content estimation models were constructed by different data transformation using PLSR, PCR and MLR methods, respectively. This study provides a fast and accurate method for monitoring regional soil salinity content and the results can provide a reference for soil salinity grading management in arid and semi-arid areas.

We demonstrate that oxygen electrocatalysts can be synchronously applied in acid oxygen evolution reaction (OER), alkaline OER and oxygen evolution reaction (ORR). The oxygen electrocatalyst (Y1.85Ba0.15Ru2O7) optimized by oxygen vacancy modulation presents an extraordinary catalytic activity and stability. Y1.85Ba0.15Ru2O7 catalyst presents an overpontential of 0.278 V in acid OER, which surpass most of the reported oxygen catalysts. Proton exchange membrane water electrolyzer (PEMWE) with Y1.85Ba0.15Ru2O7 anode attains 1.34 A cm-2 under a cell voltage of 1.7 V at 60 °C. Ba-doped Y2Ru2O7 shows an obvious advantage electrocatalytic activity than undoped Y2Ru2O7 in both OER and ORR process. This work paves a new avenue for developing active and robust oxygen electrocatalysts for both PEMWE and zinc-air battery applications.

Carbon corrosion caused by H2/O2 interface during the shut-down process is one of the factors that exacerbate the overall degradation of proton exchange membrane fuel cells (PEMFC) in automotive ap...

Cell voltage reversal resulting from hydrogen starvation at anode is one of the factors that exacerbate the overall degradation of polymer electrolyte fuel cells (PEFCs). An effective material-based mitigation strategy against cell reversal is to add oxygen evolution reaction (OER) catalysts into the anode to make reversal-tolerant-anodes (RTAs). However, RTAs still suffer from an eventual sudden death, and the failure mechanisms of this sudden death have not been well studied thus far. Here we show a novel in-situ measurement technique with a distinctive partition membrane electrode assembly (MEA) to research the failure mechanism of RTAs. It is observed for the first time that the failure of RTAs is mainly attributed to the destruction of electron conducting paths caused by carbon corrosion from catalyst layers (CLs), gas diffusion layers (GDLs) and bipolar plates (BPs), rather than deactivation of the OER catalyst. As a verification, the application of additional OER catalysts on the GDL is found to effectively prolong the reversal tolerant time. These results add significant new insights into the failure mechanism of the RTA MEA and will be of practical importance in directing to design advanced MEAs and BPs that can withstand cell voltage reversal.

Additional file 1.

The effects of four liquid modifiers (organic–inorganic composite modifier, inorganic polymer compound modifier, polyacrylate compound modifier, and organic polymer compound modifier) on plant growth, cadmium (Cd) content, photosynthetic parameters and antioxidant enzymes were studied in cotton (Xinluzao) under Cd stress (5 mg kg−1) in a barrel experiment. The results showed that the Cd treatment of soil increased Cd content in cotton and reduced plant height, net photosynthesis rate (Pn), chlorophyll fluorescence parameters, antioxidant enzyme activity, and biomass. However, the application of liquid modifiers alleviated Cd stress, increased plant biomass, and decreased Cd content in plant organs as well as Cd transport coefficients of the stem and cottonseed. At the same time, there was an increase in gas exchange, photosynthetic pigment content, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activity in cotton leaves, whereas malondialdehyde content (MDA) decreased. These results suggest a positive role of liquid modifiers in alleviating Cd stress in cotton, which was due to (1) significant reduction in Cd uptake of roots and Cd-transportation to leaves and (2) improvement in the antioxidant activity, which regulated the oxidants to a level under control, minimizing the oxidative damage in cotton.