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Formic acid (FA) has been extensively studied as one of the most promising hydrogen energy carriers today. The catalytic decarboxylation of FA ideally leads to the formation of CO2 and H2 that can be applied in fuel cells. A large number of transition‐metal based homogeneous catalysts with high activity and selectivity have been reported for the selective FA dehydrogentaion. In this review, we discussed the recent development of C,N/N,N‐ligand and pincer ligand‐based homogeneous catalysts for the FA dehydrogenation reaction. Some representative catalysts are further evaluated by the CON/COF assessment (catalyst on‐cost number)/(catalyst on‐cost frequency). Conclusive remarks are provided with future challenges and opportunities. [ABSTRACT FROM AUTHOR]

Keywords: formic acid; hydrogen energy carrier; homogeneous catalysis EN formic acid hydrogen energy carrier homogeneous catalysis 933 933 1 04/08/20 20200401 NES 200401 B Fueling the future b : Formic acid (FA) has been extensively studied as one of the most promising hydrogen energy carriers. In this Minireview, the recent development of C,N/N,N-ligand and pincer ligand-based homogeneous catalysts for the FA dehydrogenation reaction were discussed and further evaluated by the CON/COF assessment (catalyst on-cost number)/(catalyst on-cost frequency). Formic acid, hydrogen energy carrier, homogeneous catalysis. [Extracted from the article]

Formic acid possesses many desirable properties as a promising hydrogen energy carrier. Density functional theory (DFT) was utilized to design new Rh complexes with 2,2′-biimidazoline ligands to explore their potential as catalysts for formic acid dehydrogenation. These designed complexes were prepared and examined as catalysts under various temperatures and ratios of formic acid to sodium formate. It was found that although our complexes gave a high TOF of 20,000 h−1 at 90 °C under certain formic acid/sodium formate ratios, the dehydrogenation reaction was prematurely deactivated once 30% of the formic acid was consumed. Possible deactivation mechanisms were investigated by NMR and HRMS. Our observations suggest that while guided rational design of catalysts by DFT has much potential, the method does have limitations as evidenced by our experimental comparisons and thus pure DFT design should be conducted with caution. • A new Rh complex was designed by DFT and synthesized for formic acid dehydrogenation. • The designed Rh complex showed significantly enhanced reaction rates, but a short life time. • Guided rational design of catalysts using DFT has benefits but also limitations. [ABSTRACT FROM AUTHOR]

In this work, gadolinium is used to modify nickel catalyst, which can improve the properties of nickel oxide particle and inhibit its sintering and grain growth. Interface contact between nickel catalyst and YSZ is significantly improved and fine anode microstructure can be obtained when gadolinium is used to modify Ni-YSZ anode. Fine interface contact of GdNi-YSZ anode can accelerate charge transfer process and steam formation process, which leads to high activity for electrochemical oxidation of hydrogen and low impedance resistance. The remarkable characteristic of GdNi-YSZ anode cell is that the cell performance for humidified methane fuel is greatly improved due to the high anode activity for methane reforming and electrochemical oxidation of hydrogen. The maximum power density of GdNi-YSZ anode cell with humidified methane as fuel can reach 1.59 W/cm2 at 800 °C and 0.46 W/cm2 at 650 °C. High performance of GdNi-YSZ anode cell with humidified methane as fuel leads to much H 2 O produced during the electrochemical oxidation process, which can depress carbon deposition and improve the cell stability for humidified methane fuel. [Display omitted] • Interface contact of Ni-YSZ anode is significantly improved by Gd modification. • Fine interface contact accelerates charge transfer and steam formation processes. • Gd modification can improve the anode activity and cell performance for CH 4 fuel. • High cell performance leads to much H 2 O produced and good stability for CH 4 fuel. [ABSTRACT FROM AUTHOR]

• Mg 2 Ni–Ce 6 O 11 binary nanocatalyst with oxygen vacancies can be in-situ synthesized. • The peak temperature for hydrogen desorption is reduced by 115.8 °C. • The apparent activation energy for hydrogen desorption is reduced to 72.7 kJ/mol. • Synergistic catalysis of Mg 2 Ni–Ce 6 O 11 improves hydrogen sorption properties of Mg. To decrease the hydrogen sorption temperature and increase the hydrogen sorption rate is important for the practical application of magnesium for hydrogen storage. The binary nano-catalysts Mg 2 Ni and Ce 6 O 11 with oxygen vacancy defects was in-situ synthesized on Mg surface via the hydrogen activation of Mg-Ni-CeO 2. The hydrogen storage material Mg-20Ni-CeO 2 can release 4.19 wt% H 2 in 5 min at 320 °C, which is significantly higher than that of Mg with 10 wt% Ni (3.44 wt% H 2) or 10 wt% CeO 2 (0.34 wt% H 2). The peak temperature and apparent activation energy for hydrogen desorption of Mg-20Ni-CeO 2 are reduced by 115.8 °C and 63.89 kJ/mol respectively comparing with that without catalyst. Structural analysis suggests that Mg 2 Ni and Ce 6 O 11 can be in-situ synthesized on Mg surface, which shows a synergistic catalysis for hydrogen storage. During H 2 absorption, the oxygen vacancy defects on Ce 6 O 11 surface can trap H 2 molecules, while the Mg 2 Ni on Mg/Mg 2 Ni interface can promote H 2 dissociation. For H 2 desorption, the Mg 2 Ni can weaken the Mg-H bond and act as "hydrogen pump" to transfer H for H 2 formation with the assistance of Ce3+/Ce4+ transformation in Ce 6 O 11. The results of this study provide a new horizon for a novel binary catalyst design for hydrogen storage. [ABSTRACT FROM AUTHOR]