Nickel complexes as molecular catalysts for water splitting and CO2 reduction

Electro- and Solar-Driven Fuel Synthesis with First Row Transition Metal Complexes

“…29,30 Proton or CO 2 transformations mediated by molecular nickel catalysts typically involve reduction of a square-planar Ni 2+ state to a tetrahedral Ni + intermediate, and as such tetradentate ligation features prominently in the HECs outlined below. 58…”

“…This is particularly problematic when operating in aqueous media, as the generally more facile proton reduction reaction will become a significant competing process. 21,22,57,58 The relative concentrations of CO 2 (0.033 M at 298 K under 1 atm CO 2 ) 1,28 and H 2 O/H + substrates in an aqueous environment therefore provide a challenge but can be influenced by changes in pH and can even lead to direct production of industrially useful syngas (CO + H 2 ). 2,21,59,60 Selectivity for a particular product can be tuned by using molecular catalysts, with the most frequently observed products synthesized from aqueous CO 2 to date being H 2 , CO, and HCO 2 H. 21−23,58 These compounds are produced through two-electron reduction reactions and are thought to form largely as a result of a number of distinct mechanisms.…”

Computational Approach to Molecular Catalysis by 3d Transition Metals: Challenges and Opportunities

“…The utilization of multinuclear complexes providing multiple redox-active sites for CO 2 reduction is one of the promising catalyst design paths considered in the field, 446 since the redox tuning through the formation of multimetallic ensembles is considered a fruitful strategy for activity optimization of electrocatalytic systems. 449 For example, the synergistic effects of a dinickel electrocatalyst for the selective reduction of CO 2 to CO have been demonstrated in a recent combined experimental and theoretical study by Cao et al 450 The DFT-computed redox potential for Ni 2 II,II /Ni 2 I,I (−1.15 V vs NHE) coheres well with the experimental one obtained from cyclic voltammetry (−1.18 V).…”

Local ionic liquid environment at a modified iron porphyrin catalyst enhances the electrocatalytic performance of CO2 to CO reduction in water

“…[1][2][3][4][5][6] Molecular chemistry offers many handles to implement several tactics for the development and optimization of catalysts. [7][8][9][10][11][12][13][14][15][16] Iron porphyrin derivatives have been shown to be highly performing catalysts for the reduction of CO 2 to CO. 17,18 Hinging on this finding, development of more sophisticated porphyrin macrocycles holding functional groups such as proton donors or cationic units in the second coordination sphere has contributed to lowering the overpotential of this energetically demanding reaction and also to enhancing the catalytic turnover numbers and frequencies. [19][20][21] However, a recent finding that zinc porphyrins can also manage the reduction of CO 2 to CO has brought new perspectives in considering the redox participation of the porphyrin macrocycle in the observed catalytic reactivity.…”