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Hydrogen can be used as an energy carrier for renewable energy to overcome the deficiency of its intrinsically intermittent supply. One of the most promising application of hydrogen energy is on‐board hydrogen fuel cells. However, the lack of a safe, efficient, convenient, and low‐cost storage and transportation method for hydrogen limits their application. The feasibility of mainstream hydrogen storage techniques for application in vehicles is briefly discussed in this Review. Formic acid (FA), which can reversibly be converted into hydrogen and carbon dioxide through catalysis, has significant potential for practical application. Historic developments and recent examples of homogeneous noble metal catalysts for FA dehydrogenation are covered, and the catalysts are classified based on their ligand types. The Review primarily focuses on the structure−function relationship between the ligands and their reactivity and aims to provide suggestions for designing new and efficient catalysts for H2 generation from FA.

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Formic acid (FA) is considered to be a potential hydrogen storage material. Homogeneous catalysts are desired, which decompose aqueous FA into H 2 and CO 2 without addition of organic additives as they can contaminate the generated gas mixture. We report a new series of Cp*Ir (Cp* = pentamethylcyclopentadienyl) catalysts featuring picolinamide-based ligands for efficient H 2 generation from FA solution. Among them in-situ generated catalyst from [Cp*Ir(H 2 O) 3 ]SO 4 and picolinohydroxamic acid (L3) achieved a high turnover frequency (TOF) of 90625 h À 1 at 80 °C in 0.9 M FA solution and a turnover number (TON) of 120520 at 80 °C in a recycle experiment. The substituent effect of amide N atom was discussed and a plausible mechanism was proposed based on the experimental results.

To explicate the thermodynamics of the chromite ore lime-free roasting process, the thermodynamics of reactions involved in this process was calculated and the phrases of sinter with different roasting times were studied. The thermodynamics calculation shows that all the standard Gibbs free energy changes of the reactions to form Na 2 CrO 4 , Na 2 O·Fe 2 O 3 , Na 2 O·Al 2 O 3 and Na 2 O·SiO 2 via chromite ore and Na 2 CO 3 are negative, and the standard Gibbs free energy changes of the reactions between MgO, Fe 2 O 3 and SiO 2 released from chromite spinel to form MgO·Fe 2 O 3 and MgO·SiO 2 are also negative at the oxidative roasting temperatures (1 173− 1 473 K). The phrase analysis of the sinter in lime-free roasting process shows that Na 2 O·Fe 2 O 3 , Na 2 O·Al 2 O 3 and Na 2 O·SiO 2 can be formed in the first 20 min, but they decrease in contents and finally disappear with the increase of roasting time. The final phase compositions of the sinter are Na 2 CrO 4 , MgO·Fe 2 O 3 , MgO·SiO 2 and MgO. The results indicate that Na 2 CrO 4 can be formed easily via the reaction of Na 2 CO 3 with chromite ore. Na 2 O·Fe 2 O 3 , Na 2 O·Al 2 O 3 and Na 2 O·SiO 2 can be formed as intermediate compounds in the roasting process and they can further react with chromite ore to form Na 2 CrO 4 . MgO released from chromite ore may react with iron oxides and silicon oxide to form stable compounds of MgO·Fe 2 O 3 and MgO·SiO 2 , respectively.