Tilmann Joachim Neubert

Effusion measurements are performed to determine the hydrogen concentration and its binding energies in large area graphene. The samples were grown by chemical vapor deposition using deuterium and deuterated methane as readily identifiable isotopes that duplicate hydrogen chemistry. In a second step, graphene is transferred to silicon substrates covered with an oxide layer of different thickness. H binding energies and the H density‐of‐states distributions are derived from the effusion spectra. The data show a well defined peak in the H density‐of‐states at 1.97 eV that is influenced by the thickness of the oxide layer. This is discussed in terms of a model that describes the dissociation of C−H bonds.

Supercapacitors, also commonly known as ‘ultracapacitors’, represent a promising alternative for meeting the escalating power demands of energy storage systems, particularly within the realm of portable electronic devices and batteries in the automotive sector

Anthropogenic emissions of previously sequestered carbon continue to disrupt the natural carbon cycle, driving atmospheric carbon dioxide (CO ₂ ) concentrations beyond 420 ppm. This has resulted in global temperatures rising beyond 1.5 °C above the pre‐industrial level. Direct air capture (DAC) of CO ₂ has emerged as a complementary mitigation strategy. However, current DAC technologies are limited by the high energy requirements inherent to the thermal release of captured CO ₂ , which are caused by the low thermodynamic efficiency of heat‐driven processes, as constrained by Carnot principles. Redox‐mediated electrochemical carbon capture (RMECC) offers a promising pathway to overcome these limitations. RMECC with DAC application remains in an early developmental stage and requires further optimization to enable energy‐efficient, cost‐effective, and scalable deployment. In this perspective the design of sorbents, electrolytes, and electrochemical cell configurations in the field of RMECC are discussed with an emphasis on sustainable approaches for the demands of DAC applications. The challenges arising from the atmospheric dilution of CO ₂ within the more abundant and disruptive competitor oxygen are highlighted as a critical factor influencing sorbent performance. Recent advancements in RMECC are reviewed, key challenges are identified, and future directions are outlined to accelerate electrochemically mediated DAC towards practical implementation.

The next generation of adhesives requires effective debonding capabilities that can be triggered on demand to enable advanced circular repair and recycling strategies. A new class of lignin‐inspired, two‐component (2K) structural adhesives offers bonding strengths of up to 20 MPa and clean, on‐command electrochemical debonding within 5–30 min. The debonding is induced by a distinct electrochemical oxidation of thiol‐catechol connectivities (TCCs) within the entire adhesive network, enforcing rapid and clean adhesive failure on the cathodic substrate side. The TCC‐functionalities are formed during curing by a thiol‐quinone Michael ‐type polyaddition, reacting polyester‐based trithiols with tris‐quinones as lignin‐inspired minimal building blocks. The structural adhesive can be fine‐tuned by adjusting the formulation. The addition of carbon black and ionic liquids facilitates the desired electrochemical transformation of TCC‐catechols to TCC‐quinones. Applying only 9 V for 5–30 min, leads to clean debonding with 72–86% loss of shear strength. A comprehensive study of curing, bonding, and debonding behavior by rheological, spectroscopic, and electrochemical investigations reveals the debonding mechanism by correlating catechol oxidation to adhesive performance. The electrochemical debonding capability of TCC‐structural adhesives is demonstrated in a functional prototype, where on‐command detachment of a cover glass from a display device is achieved within 6.5 min.

Multifunktionelle ortho‐Chinone werden für die Bildung von Thiol‐Catechol‐Verknüpfungen (engl. thiol‐catechol‐connectivity, TCC) benötigt, sind jedoch empfindlich in der Handhabung. Die elektrochemische Oxidation des Dipeptids DiDOPA vom Catechol zum ortho‐Chinon wird hier mit einer optimierten Umwandlungseffizienz von bis zu 92 % vorgestellt. Die Elektrosynthese erfolgte an kostengünstigen Graphit‐ und Edelstahlelektroden. Durch die elektrochemische Aktivierung werden Chinon‐Lösungen erzeugt, die frei von unerwünschten reaktiven Verbindungen sind, wodurch die anspruchsvolle Isolierung instabiler Chinone entfällt. Die DiDOPA‐Chinone wurden in Polyadditionsreaktionen mit Multithiolen eingesetzt und bildeten Oligomere, die als transiente Enzymstabilisatoren (TES) fungieren. Bei Verwendung der TCC‐TES‐Oligomere als Additive in Hitzebelastungstests wurde ein Stabilisierungseffekt für Tyrosinase beobachtet. Die Anwesenheit der TCC‐TES schützte das Enzym bei thermischem Stress vor Denaturierung und Aktivitätsverlusten.

Multifunctional ortho‐quinones are required for the formation of thiol‐catechol‐connectivities (TCC) but can be delicate to handle. We present the electrochemical oxidation of the dipeptide DiDOPA, achieving up to 92 % conversion efficiency of the catechols to ortho‐quinones. Graphite and stainless steel could be employed as cost‐efficient electrodes. The electrochemical activation yields quinone‐solutions, which are free of undesired reactive compounds and eliminates the challenging step of isolating the reactive quinones. The DiDOPA quinones were employed in polyaddition reactions with multi‐thiols, forming oligomers that functioned as transient enzyme stabilizers (TES). These TCC‐TES‐additives improved the thermal stability and the activity of tyrosinase in heat stress assays.

Debondable pressure‐sensitive adhesives (PSAs) promise access to recyclability in microelectronics in the transition toward a circular economy. Two PSAs were synthesized from a tetravalent thiol star‐polyester forming thiol‐catechol‐connectivities (TCC) with either the biorelated DiDopa‐bisquinone (BY*Q) or the fossil‐based bisquinone A (BQA). The PSAs enable debonding by oxidation of TCC‐catechols to quinones. The extent of debonding efficiency depends on the interaction modes, which are determined by the chemical structure differences of both TCC‐motifs. BY*Q‐TCC‐PSA debonds with exceptional loss of 99 % of its approx. 2 MPa shear strength in glass‐on‐glass junctions. For BQA‐TCC‐PSA, a debonding efficiency of only approx. 60 % was found, irrespective of its initial shear strength, which could be tuned up to approx. 7 MPa. The efficiency of debonding for BY*Q‐TCC‐PSA after TCC‐oxidation is linked to the loss of synergistic interactions without strongly affecting the bulk glue properties, outperforming the purely catechol‐based BQA‐analogue.

Soft substrates are interesting for many applications, ranging from mimicking the cellular microenvironment to implants. Conductive electrodes on such substrates allow the realization of flexible, elastic, and transparent sensors. Single-layer graphene as a candidate for such electrodes brings the advantage that the active area of the sensor is transparent and conformal to the underlying substrate. Here, we overcome several challenges facing the routine realization of graphene cell sensors on a canonical soft substrate, namely, poly-(dimethylsiloxane) (PDMS). We have systematically studied the effect of surface energy before, during, and after the transfer of graphene. Thus, we have identified a suitable support polymer, optimal substrate (pre)-treatment, and an appropriate solvent for the removal of the support. Using this procedure, we can reproducibly obtain stable and intact graphene sensors on a millimeter scale on PDMS, which can withstand continuous measurements in cell culture media for several days. From local nanomechanical measurements, we infer that the softness of the substrate is slightly affected after the graphene transfer. However, we can modulate the stiffness using PDMS with differing compositions. Finally, we show that graphene sensors on PDMS can be successfully used as soft electrodes for real-time monitoring of the cell adhesion kinetics. The routine availability of single-layer graphene electrodes on a soft substrate with tunable stiffness will open a new avenue for studies, where the PDMS-liquid interface is made conducting with minimal alteration of the intrinsic material properties such as softness, flexibility, elasticity, and transparency.

Artificial van der Waals heterostructures, obtained by stacking two‐dimensional (2D) materials, represent a novel platform for investigating physicochemical phenomena and applications. Here, the electrochemistry at the one‐dimensional (1D) edge of a graphene sheet, sandwiched between two hexagonal boron nitride (hBN) flakes, is reported. When such an hBN/graphene/hBN heterostructure is immersed in a solution, the basal plane of graphene is encapsulated by hBN, and the graphene edge is exclusively available in the solution. This forms an electrochemical nanoelectrode, enabling the investigation of electron transfer using several redox probes, e.g., ferrocene(di)methanol, hexaammineruthenium, methylene blue, dopamine and ferrocyanide. The low capacitance of the van der Waals edge electrode facilitates cyclic voltammetry at very high scan rates (up to 1000 V s⁻¹), allowing voltammetric detection of redox species down to micromolar concentrations with sub‐second time resolution. The nanoband nature of the edge electrode allows operation in water without added electrolyte. Finally, two adjacent edge electrodes are realized in a redox‐cycling format. All the above‐mentioned phenomena can be investigated at the edge, demonstrating that nanoscale electrochemistry is a new application avenue for van der Waals heterostructures. Such an edge electrode will be useful for studying electron transfer mechanisms and the detection of analyte species in ultralow sample volumes.