DFT studies suggest that PI Catalysts, when activated, provide a metal alkyl in the cis position to a vacant coordination site for monomer binding.
X-ray analyses as well as 1H NMR studies demonstrate that bis(pyrrolide-imine) Ti complexes (named PI Catalysts) contain approximately octahedrally coordinated metal centers with mutually trans-pyrrolide-Ns, cis-imine-Ns and cis-Cls.
These theoretical studies also show that the active species derived from PI Catalysts normally possess higher electrophilicity and a sterically more open nature compared with those produced using bis phenoxy-imine) Ti complexes (Ti–FI Catalysts) which are known as high performance olefin polymerization catalysts.
The enhancement in oxygen reduction reaction (ORR) activity is achieved by the introduction of Fe species via the Fe electrochemical deposition-dissolution treatment into a metal-free nitrogen-doped carbon (P-PI) catalyst, which is prepared by the pyrolysis of polyimide fine particles.
The thus-obtained Fe-containing P-PI catalyst suffers activity decay during the durability test, evidenced by the negative shift of half-wave potential, the decrease in limiting current density, the number of electrons transferred, and the ratio of the rate constant for 4-electron ORR to that for 2-electron process, and the increase in H2O2 production percentage.
In comparison with bare ZnO, which has an onset potential of 0.5 V (vs. RHE), the photocurrent onset is cathodically shifted by about 0.1 V (vs. RHE) for Co-Pi-modified ZnO, which is attributed to the Co-Pi catalyst mitigating hole electron recombination by acting as a hole-trapping site to increase charge-separation efficiency.
After coupling with Co-Pi catalysts, the hematite sample can even achieve a stable, high photocurrent of 2.90 matcm2 at 1.23 V vs. RHE.
We found out that at a pressure of ∼3 GPa and temperature of >2400 K generated from NVT processes, layered graphene clusters were crystallized from PI without metal catalysts, which is consistent with previous experimental results.
Among these OECs, the Co-Pi and FeOOH catalysts can lead to a negative-shift of onset potentials of water oxidation and effectively enhance the magnitude of photocurrent [7, 9, 19].
The loading of water-oxidation catalysts [Co-Pi and nickel borate (Ni-B)] on ZnO for efficient photoelectrochemical water splitting was investigated.
Both Co-Pi and Ni-B catalysts were deposited onto optimized ZnO films by photoassisted electrodeposition.[ 27– 28] A three-electrode system with as-prepared ZnO films as working electrode, Ag/AgCl as reference electrode, and a Pt mesh as counter electrode were used for the photoassisted electrodeposition process.
