Kazuhiro Takanabe

A widely used term, “photocatalysis”, generally addresses photocatalytic (energetically down-hill) and photosynthetic (energetically up-hill) reactions and refers to the use of photonic energy as a driving force for chemical transformations, i.e., electron reorganization to form/break chemical bonds. Although there are many such important reactions, this contribution focuses on the fundamental aspects of photocatalytic water splitting into hydrogen and oxygen by using light from the solar spectr

The challenge in the electrochemical reduction of aqueous carbon dioxide is in designing a highly selective, energy-efficient, and non-precious-metal electrocatalyst that minimizes the competitive reduction of proton to form hydrogen during aqueous CO2 conversion. A non-noble metal electrocatalyst based on a copper-indium (Cu-In) alloy that selectively converts CO2 to CO with a low overpotential is reported. The electrochemical deposition of In on rough Cu surfaces led to Cu-In alloy surfaces. D

Spectral sensitization of a mesoporous graphite carbon nitride (mpg-C(3)N(4)) photocatalyst was investigated by depositing magnesium phthalocyanine (MgPc) to expand the absorption to wavelengths longer than those of the principal mpg-C(3)N(4). The obtained sample, MgPc/Pt/mpg-C(3)N(4) (Pt as a cocatalyst) showed stable photocatalytic evolution of hydrogen from aqueous solution in the presence of sacrificial reagents (triethanolamine), even under irradiation at wavelengths longer than 600 nm. Inc

Described herein is the photocatalytic hydrogen evolution using crystalline carbon nitrides (CNs) obtained by supramolecular aggregation followed by ionic melt polycondensation (IMP) using melamine and 2,4,6-triaminopyrimidine as a dopant. The solid state NMR spectrum of (15)N-enriched CN confirms the triazine as a building unit. Controlling the amount and arrangements of dopants in the CN structure can dramatically enhance the photocatalytic performance for H2 evolution. The polytriazine imide

Recent advances in power generation from renewable resources necessitate conversion of electricity to chemicals and fuels in an efficient manner. Electrocatalytic water splitting is one of the most powerful and widespread technologies. The development of highly efficient, inexpensive, flexible, and versatile water electrolysis devices is desired. This review discusses the significance and impact of the electrolyte on electrocatalytic performance. Depending on the circumstances under which the wa

Tungsten carbide exhibits platinum-like behavior, which makes it an interesting potential substitute for noble metals in catalytic applications. Tungsten carbide nanocrystals (≈5 nm) are directly synthesized through the reaction of tungsten precursors with mesoporous graphitic C(3)N(4) (mpg-C(3)N(4)) as the reactive template in a flow of inert gas at high temperatures. Systematic experiments that vary the precursor compositions and temperatures used in the synthesis selectively generate differen

Highly active NiFeO_x electrocatalysts for the oxygen evolution reaction (OER) suffer gradual deactivation with time owing to the loss of Fe species from the active sites into solution during catalysis. The anodic deposition of a CeO_x layer prevents the loss of such Fe species from the OER catalysts, achieving a highly stable performance. The CeO_x layer does not affect the OER activity of the catalyst underneath but exhibits unique permselectivity, allowing the pe

Kinetic and isotopic methods were used to determine the identity, rate constants, and reversibility of elementary steps for primary and secondary reactions involved in the oxidative coupling of methane (OCM) on Mn/Na2WO4/SiO2. We provide evidence in this study for parallel C−H bond activation pathways, in which H-abstraction is mediated by either oxygen species on surfaces or by OH radicals formed via H2O/O2 equilibration on catalyst surfaces. OCM rates and C2+ yields are higher when H2O is pres

Recent spectroscopic and computational studies concerning the oxygen evolution reaction over iridium oxides are reviewed to provide the state-of-the-art understanding of its reaction mechanism.

A Ni–Mo composite functions as a promising non-noble metal electrocatalyst for the hydrogen evolution reaction (HER) in alkaline water. Despite its industrial relevance, the kinetic origin of the high catalytic activity remains under debate. The present report discusses a reaction mechanism of HER on Ni–Mo catalysts by combining experimental and theoretical studies. In contrast to a Ni catalyst, a Ni–Mo catalyst is insensitive to CO gas introduced during HER. In situ spectroscopic measurements i

Active Mo₂C–C nanocomposites were synthesized using an mpg-C₃N₄ template and demonstrated as active electrocatalysts for the hydrogen evolution reaction.