@article{nokey,

title = {Designing multifunctional CoOx layers for efficient and stable electrochemical energy conversion},

author = {M Kuhl and A Henning and L Haller and L Wagner and C-M Jiang and V Streibel and I Sharp and J Eichhorn},

doi = {10.26434/chemrxiv-2022-23ck4},

year  = {2022},

date = {2022-01-13},

journal = {Cambridge: Cambridge Open Engage},

abstract = {Disordered and porous metal oxides are promising as earth-abundant and cost-effective alternatives to noble-metal electrocatalysts. Herein, we leverage non-saturated oxidation in plasma-enhanced atomic layer deposition to tune structural, mechanical, and optical properties of biphasic CoOx thin films, thereby tailoring their catalytic activities and chemical stabilities. To optimize the resulting film properties, we systematically vary the oxygen plasma power and exposure time in the deposition process. We find that short exposure times and low plasma powers incompletely oxidize the cobaltocene precursor to Co(OH)2 and result in the incorporation of carbon impurities. These Co(OH)2 films are highly porous and catalytically active, but their electrochemical stability is impacted by poor adhesion to the substrate. In contrast, long exposure times and high plasma powers completely oxidize the precursor to form Co3O4, reduce the carbon impurity incorporation, and improve the film crystallinity. While the resulting Co3O4 films are highly stable under electrochemical conditions, they are characterized by low oxygen evolution reaction activities. To overcome these competing properties, we applied the established relation between deposition parameters and functional film properties to design bilayer films exhibiting simultaneously improved electrochemical performance and chemical stability. The resulting biphasic films combine a highly active Co(OH)2 surface with a stable Co3O4 interface layer. In addition, these coatings exhibit minimal light absorption, thus rendering them well suited as protective catalytic layers on semiconductor light absorbers for application in photoelectrochemical devices.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {2D/3D Hybrid Cs2AgBiBr6 Double Perovskite Solar Cells: Improved Energy Level Alignment for Higher Contact-Selectivity and Large Open Circuit Voltage},

author = {M T Sirtl and R Hooijer and M Armer and F G Ebadi and M Mohammadi and C Maheu and A Weis and B T Van Gorkom and S H\"{a}ringer and R J Janssen and T Mayer and V Dyakonov and W Tress and T Bein},

url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aenm.202103215},

doi = {https://doi.org/10.1002/aenm.202103215},

issn = {1614-6832},

year  = {2022},

date = {2022-01-09},

journal = {Advanced Energy Materials},

volume = {n/a},

number = {n/a},

pages = {2103215},

abstract = {Abstract Since their introduction in 2017, the efficiency of lead-free halide perovskite solar cells based on Cs2AgBiBr6 has not exceeded 3%. The limiting bottlenecks are attributed to a low electron diffusion length, self-trapping events and poor selectivity of the contacts, leading to large non-radiative VOC losses. Here, 2D/3D hybrid double perovskites are introduced for the first time, using phenethyl ammonium as the constituting cation. The resulting solar cells show an increased efficiency of up to 2.5% for the champion cells and 2.03% on average, marking an improvement by 10% compared to the 3D reference on mesoporous TiO2. The effect is mainly due to a VOC improvement by up to 70 mV on average, yielding a maximum VOC of 1.18 V using different concentrations of phenethylammonium bromide. While these are among the highest reported VOC values for Cs2AgBiBr6 solar cells, the effect is attributed to a change in recombination behavior within the full device and a better selectivity at the interface toward the hole transporting material (HTM). This explanation is supported by voltage-dependent external quantum efficiency, as well as photoelectron spectroscopy, revealing a better energy level alignment and thus a better hole-extraction and improved electron blocking at the HTM interface.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}

@article{nokey,

title = {Nickel polyphthalocyanine with electronic localization at the nickel site for enhanced CO2 reduction reaction},

author = {K Chen and M Cao and G Ni and S Chen and H Liao and L Zhu and H Li and J Fu and J Hu and E Cort\'{e}s and M Liu},

url = {https://www.sciencedirect.com/science/article/pii/S0926337322000339},

doi = {https://doi.org/10.1016/j.apcatb.2022.121093},

issn = {0926-3373},

year  = {2022},

date = {2022-01-09},

journal = {Applied Catalysis B: Environmental},

volume = {306},

pages = {121093},

abstract = {Nickel phthalocyanine (NiPc) can be at first glance a compelling catalyst for CO2 reduction reaction (CO2RR) because of its Ni\textendashN4 site. Unfortunately, the pristine NiPc possesses a low catalytic activity resulting from the poor CO2 adsorption and activation capabilities of the electron-deficiency Ni site. Herein, we develop nickel polyphthalocyanine (NiPPc) with extended conjugation to tailor the electronic density at the Ni active site. The enlarged π conjugation of NiPPc evokes the d-electrons localization, increasing the electronic density at the Ni site, which enhances its CO2 adsorption and activation. Consequently, NiPPc supported on carbon nanotubes (NiPPc/CNT) in a flow cell delivers an excellent activity of −300 mA cm−2 for CO2RR with the CO selectivity of 99.8%, which is much higher than that of NiPc dispersed on carbon nanotubes. NiPPc/CNT exhibits an outstanding stability for CO2RR of more than 30 h at a current density of −100 mA cm−2 with an ultrahigh selectivity for CO, exceeding 99.7%. This work showcases a new way of tuning the electronic density of catalytic sites.},

keywords = {},

pubstate = {published},

tppubtype = {article}

}