This paper reviews recent progress made in identifying electrocatalysts for carbon dioxide (CO2) reduction to produce low-carbon fuels, including CO, HCOOH/HCOO−, CH2O, CH4, H2C2O4/HC2O4−, C2H4, CH3OH, CH3CH2OH and others. The electrocatalysts are classified into several categories, including metals, metal alloys, metal oxides, metal complexes, polymers/clusters, enzymes and organic molecules. The catalyts' activity, product selectivity, Faradaic efficiency, catalytic stability and reduction mechanisms during CO2 electroreduction have received detailed treatment. In particular, we review the effects of electrode potential, solution–electrolyte type and composition, temperature, pressure, and other conditions on these catalyst properties. The challenges in achieving highly active and stable CO2 reduction electrocatalysts are analyzed, and several research directions for practical applications are proposed, with the aim of mitigating performance degradation, overcoming additional challenges, and facilitating research and development in this area.

A review of catalysts for the electroreduction of carbon dioxide to produce low-carbon fuels

The increase in atmospheric carbon dioxide is linked to climate changes; hence there is an urgent need to reduce the accumulation of CO2 in the atmosphere. The utilization of CO2 as a raw material in the synthesis of chemicals and liquid energy carriers offers a way to mitigate the increasing CO2 buildup. This review covers six important CO2 transformations namely: chemical transformations, photochemical reductions, chemical and electrochemical reductions, biological conversions, reforming and inorganic transformations. Furthermore, the vast research area of carbon capture and storage is reviewed briefly. This review is intended as an introduction to CO2, its synthetic reactions and their possible role in future CO2 mitigation schemes that has to match the scale of man-made CO2 in the atmosphere, which rapidly approaches 1 teraton.

The teraton challenge. A review of fixation and transformation of carbon dioxide

Research in the field of catalytic reduction of carbon dioxide to liquid fuels has grown rapidly in the past few decades. This is due to the increasing amount of carbon dioxide in the atmosphere and a steady climb in global fuel demand. This tutorial review will present much of the significant work that has been done in the field of electrocatalytic and homogeneous reduction of carbon dioxide over the past three decades. It will then extend the discussion to the important conclusions from previous work and recommendations for future directions to develop a catalytic system that will convert carbon dioxide to liquid fuels with high efficiencies.

Electrocatalytic and homogeneous approaches to conversion of CO2 to liquid fuels

Two major energy-related problems confront the world in the
next 50 years. First, increased worldwide competition for
gradually depleting fossil fuel reserves (derived from past
photosynthesis) will lead to higher costs, both monetarily and politically. Second, atmospheric CO_2 levels are at their highest recorded level since records began. Further increases are predicted to produce large and uncontrollable impacts on the world climate. These projected impacts extend beyond climate to ocean acidification, because the ocean is a major sink for atmospheric CO2.1 Providing a future energy supply that is secure and CO_2-neutral will require switching to nonfossil energy sources such as wind, solar, nuclear, and geothermal energy and developing methods for transforming the energy produced by these new sources into forms that can be stored, transported, and used upon demand.

Frontiers, Opportunities, and Challenges in Biochemical and Chemical Catalysis of CO2 Fixation

The direct and catalyzed electrochemistry of CO2 partake in the contemporary attempts to reduce this inert molecule to fuels by means of solar energy, either directly, after conversion of light to electricity, or indirectly in that all elements of comprehension derived from electrochemical experiments can be used in the design and interpretation of photochemical experiments. Following reviews of the activity in the field until 2007–2008, the present review reports more recent findings even if their interpretation remains uncertain. It also develops useful notions that allow analyzing and comparing more rigorously the performances of existing catalysts when the necessary data are available. Among the general trends that transpire presently and are likely to be the object of active future work emphasis is put on the favorable role of acid addition in homogeneous catalytic systems and on the crucial chemical role of the electrode material in heterogeneous catalysis.

Catalysis of the electrochemical reduction of carbon dioxide

Electrochemical reduction of CO2 catalyzed by [Pd(triphosphine)(solvent)](BF4)2 complexes : synthetic and mechanistic studies

Total synthesis of the first molecular Moebius strip

Nickel and palladium complexes of the type (M(L{sub 2}){sub 2})(BF{sub 4}){sub 2} and (M(L{sub 2})(L{sub 2}{prime}))(BF{sub 4}){sub 2} (where L{sub 2} and L{sub 2}{prime} are diphosphine ligands) have been synthesized. The lowest energy electronic absorption band for the nickel complexes decreases in energy as the bite size of the diphosphine ligand increases. Similarly, the half-wave potentials for the Ni(II/I) and Pd(II/O) couples become more positive as the bite size increases. Structural studies of (Ni(dppm){sub 2})(BF{sub 4}){sub 2} (where dppm is bis(diphenylphosphino)methane) and (Ni-(dppb){sub 2})(PF{sub 6}){sub 2} (where dppb is 1,2-bis(diphenylphosphino)benzene) show that increasing the bite size of the diphosphine ligands results in larger tetrahedral distortions. The crystal structure of (Ni(Dppm){sub 2})(BF{sub 4}){sub 2}(C{sub 50}H{sub 44}B{sub 2}F{sub 8}NiP{sub 4}) and (Ni(Dppb){sub 2})(PF{sub 6}){sub 2}(C{sub 74}H{sub 64}F{sub 12}NiP{sub 6}) were measured and are reported herein. Calculations made using the extended Huckel theory indicate that the observed distortions may have an electronic as well as a steric component. The calculations also allow rationalization of the electronic absorption spectra, electrochemical data, and the stability of the Ni(I) and Pd(I) complexes (Ni(dppp){sub 2})(BF{sub 4}) (where dppp is 1,3-bis(diphenylphosphino)propane) and (Pd(dppx){sub 2})(BF{sub 4}) (where dppx is {alpha},{alpha}{prime}-bis(diphenylphosphino)-o-xylene). Complexes containing the ligand dppm have a marked tendencymore » to become five-coordinate, as indicated by the structural determination of (Ni(dppm){sub 2}(CH{sub 3}CN))(PF{sub 6}){sub 2}. The crystal structure for the latter complex is reported.« less

Relationship between the bite size of diphosphine ligands and tetrahedral distortions of square-planar nickel(ii) complexes : stabilization of nickel( i) and palladium(i) complexes using diphosphine ligands with large bites

New (malonato)platinum(II) compounds, cis-[Pt(OOCACOO)(Me 2 SO) 2 ] (A=CH 2 , cycloalkyl), have been prepared, and their reactions with various amines have led to a new general synthesis of antitumor symmetrical and dissymmetrical (malonato)platinum(II) complexes. Reaction of trans-(―)-1,2-cyclohexanediamine (CHDA) with the cyclobutanedicarboxylate (CBDC) complex cis-[Pt(CBDC)(Me 2 SO) 2 ] has been studied in detail, and crystallographic molecular structure determinations have been carried out on the Pt(CHDA)(Me 2 SO)(CBDC) intermediate and the Pt(CHDA)(CBDC) product

(Malonato)bis[sulfinylbis[methane]-S]platinum(II) compounds: versatile synthons for a new general synthesis of antitumor symmetrical and dissymmetrical (malonato)platinum(II) complexes

The new 1,3,2,4-diazadiphosphetidines cis- and trans-[(MeNH)PNMe] 2 (8, 9), cis- and trans-[(EtNH)PNEt] 2 (10, 11), cis- and trans-[(i-PrNH)PN-i-Pr] 2 (13, 14), [(MeNH)P(S)NMe] 2 (16), trans-[(EtNH)P(S)NEt] 2 (17) [(i-PrNH)P(S)N-i-Pr] 2 (19), cis- [(t-BuNH)P(S)N-t-Bu] 2 (20), and the cage compounds P 4 (NEt) 6 (12) and P 4 S 4 (NEt) 6 (18) have been prepared and characterized

R. Curtis Haltiwanger

Papers

Electrochemical reduction of CO2 catalyzed by [Pd(triphosphine)(solvent)](BF4)2 complexes : synthetic and mechanistic studies

Total synthesis of the first molecular Moebius strip

Relationship between the bite size of diphosphine ligands and tetrahedral distortions of square-planar nickel(ii) complexes : stabilization of nickel( i) and palladium(i) complexes using diphosphine ligands with large bites

(Malonato)bis[sulfinylbis[methane]-S]platinum(II) compounds: versatile synthons for a new general synthesis of antitumor symmetrical and dissymmetrical (malonato)platinum(II) complexes

Cis/trans isomerization and conformational properties of 2,4-bis(primary amino)1,3,2,4-diazadiphosphetidines