Several Key Factors for Efficient Electrocatalytic Water Splitting: Active Site Coordination Environment, Morphology Changes and Intermediates Identification

Abstract

Water-splitting has emerged as a promising alternative strategy to produce clean hydrogen fuel. However, current electrocatalytic water splitting suffers from sluggish kinetics, thus developing efficient electrocatalysts is crucial. Identifying reaction centers discloses the reaction mechanism and will undoubtedly facilitate the design and optimization of efficient water splitting electrocatalysts. This review summarizes several advances involving the identification of the actual active sites and intermediates capture on the catalytic surface. The morphology and valence states change on 2D materials are chose to illustrate how structural evolution affect catalytic activity. Specifically, in situ/ex situ electron microscopy techniques that used for the characterization of catalytic sites, and spectroscopy techniques that used to detect active intermediates at the molecular level are highlighted. In addition, several perspectives, such as the development of new in situ techniques and electrokinetic analysis methods, are emphasized to shed light on future research.

Revealing Spin Magnetic Effect of Iron-Group Layered Double Hydroxides with Enhanced Oxygen Catalysis

“…61,62 The Raman spectra show representative bands at 528 cm −1 , which belong to the M II −O−Fe III , respectively. 63,64 When the voltage increases, the structural changes occurred in the LDH catalysts with application of an oxidation potential. The peaks at 470 cm −2 and 553 cm −1 were ascribed to the M III −O−O−Fe III in NCFL under the operating potentials.…”

“…In the iron group LDHs, the magnetic transition metals can undergo spin hybridization with 2p of oxygenated intermediates, thereby increasing the spin-charge transfer kinetics that would optimize the three-phase interface and promote charge transport. – As shown in Figure a, under an external magnetic field, the spin exchange between the orbit of the ferromagnetic catalyst and the adsorbed oxygenated intermediate would be enhanced to achieve magnetically improved OER activity. To study the catalytic mechanism, the operando Raman spectrum was performed to detect the intermediates at applied potentials ranging from OCV to 1.8 V for NCFL as shown in Figure b. , The Raman spectra show representative bands at 528 cm –1 , which belong to the M II –O–Fe III , respectively. , When the voltage increases, the structural changes occurred in the LDH catalysts with application of an oxidation potential. The peaks at 470 cm –2 and 553 cm –1 were ascribed to the M III –O–O–Fe III in NCFL under the operating potentials.…”

Solvent modulation of the morphology of homochiral gadolinium coordination polymers and its impact on circularly polarized luminescence

“…1,2 Typical examples are metal–organic frameworks (MOFs) that show morphology-dependent catalytic performance due to their different expressing crystal faces. 3 Studying the effect of morphology on the optical properties of chiral molecular materials, such as the circularly polarized luminescence (CPL), is another interesting issue that is important for the development of CPL-active materials for applications. 4 CPL is a unique chiroptical property of chiral luminescent systems, and its application requires CPL emission with high quantum yield and a large dissymmetry factor, which is defined as g lum = 2( I L − I R )/( I L + I R ), where I L and I R refer to the intensities of left- and right-handed circularly polarized emissions.…”