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Sustainable production of hydrogen gas, a green energy carrier of high density, is possible only by electrolysis of water based on the hydrogen evolution reaction (HER). Here, we report the effect of oxygen poisoning on the efficiency of hydrogen production and the consumption by the HER and the hydrogen oxidation reaction (HOR), respectively, on the interface of platinum group metal-free electrocatalyst TaS2 in pristine form and intercalated by the organic Lewis base hexylamine. The state of the surface probed by photoelectron spectroscopy was significantly altered by both Lewis base doping and oxygen poisoning. This alteration dramatically affects the hydrogen production efficiency in the HER, while the back process by the HOR was less sensitive to the changes in the surface states of the electrocatalysts. The oxygenated and intercalated electrocatalyst shows more than 2 x 105 times lower exchange current density of the HER compared to pristine oxygenated materials., Funding Agencies|Swedish Research Council [VR 2016-05990, VR 2020-04210]; Knut and Alice Wallenberg Foundation [KAW 2019.0604, 2021.0195]; Karl Erik O nnesjoes Foundation; Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoeping University (Faculty Grant SFO-Mat-LiU) [2009-00971]

Hydrogen technology, as a future breakthrough for the energy industry, has been defined as an environmentally friendly, renewable, and high-power energy carrier. The green production of hydrogen, which mainly relies on electrocatalysts, is limited by the high cost and/ or the performance of the catalytic system. Recently, studies have been conducted in search of bifunctional electrocatalysts accelerating both the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR). Herein, we report the investigation of the high efficiency bifunctional electrocatalyst TaS2 for both the HER and the HOR along with the asymmetric effect of inhibition by organic intercalation. The linear organic agent, to boost the electron donor property and to ease the process of intercalation, provides a higher interlayer gap in the tandem structure of utilized nanosheets. XRD and XPS data reveal an increase in the interlayer distance of 22%. The HER and the HOR were characterized in a Pt group metal-free electrochemical system. The pristine sample shows a low overpotential of -0.016 Vat the onset. The intercalated sample demonstrates a large shift in its performance for the HER. It is revealed that the intercalation is a potential key strategy for tuning the performance of this family of catalysts. The inhibition of the HER by intercalation is considered as the increase in the operational window of a water-based electrolyte on a negative electrode, which is relevant to technologies of electrochemical energy storage., Funding Agencies|Swedish Research Council [VR 2016-05990]; Knut and Alice Wallenberg Foundation [KAW 2019.0604, 2021.0195]; Karl Erik Onnesjos Foundation; Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials at Linkoping University (Faculty Grant SFO-MatLiU) [2009-00971]

Printed electronics implies the use of low-cost, scalable, printing technologies to fabricate electronic devices and circuits on flexible substrates, such as paper or plastics. The development of this new electronic is currently expanding because of the emergence of the internet-of-everything. Although lot of attention has been paid to functional inks based on organic semiconductors, another class of inks is based on nanoparticles obtained from exfoliated 2D materials, such as graphene and metal sulfides. The ultimate scientific and technological challenge is to find a strategy where the exfoliated nanoparticle flakes in the inks can, after solvent evaporation, form a solid which displays performances equal to the single crystal of the 2D material. In this context, a printed layer, formed from an ink composed of nano-flakes of TiS2 intercalated with hexylamine, which displays thermoelectric properties superior to organic intercalated TiS2 single crystals, is demonstrated for the first time. The choice of the fraction of exfoliated nano-flakes appears to be a key to the forming of a new self-organized layered material by solvent evaporation. The printed layer is an efficient n-type thermoelectric material which complements the p-type printable organic semiconductors The thermoelectric power factor of the printed TiS2/hexylamine thin films reach record values of 1460 mu W m(-1) K-2 at 430 K, this is considerably higher than the high value of 900 mu W m(-1) K-2 at 300 K reported for a single crystal. A printed thermoelectric generator based on eight legs of TiS2 confirms the high-power factor values by generating a power density of 16.0 W m(-2) at Delta T = 40 K., Funding Agencies|Knut och Alice Wallenbergs StiftelseKnut & Alice Wallenberg Foundation