@article{14828, abstract = {Production of hydrogen at large scale requires development of non-noble, inexpensive, and high-performing catalysts for constructing water-splitting devices. Herein, we report the synthesis of Zn-doped NiO heterostructure (ZnNiO) catalysts at room temperature via a coprecipitation method followed by drying (at 80 °C, 6 h) and calcination at an elevated temperature of 400 °C for 5 h under three distinct conditions, namely, air, N2, and vacuum. The vacuum-synthesized catalyst demonstrates a low overpotential of 88 mV at −10 mA cm–2 and a small Tafel slope of 73 mV dec–1 suggesting relatively higher charge transfer kinetics for hydrogen evolution reactions (HER) compared with the specimens synthesized under N2 or O2 atmosphere. It also demonstrates an oxygen evolution (OER) overpotential of 260 mV at 10 mA cm–2 with a low Tafel slope of 63 mV dec–1. In a full-cell water-splitting device, the vacuum-synthesized ZnNiO heterostructure demonstrates a cell voltage of 1.94 V at 50 mA cm–2 and shows remarkable stability over 24 h at a high current density of 100 mA cm–2. It is also demonstrated in this study that Zn-doping, surface, and interface engineering in transition-metal oxides play a crucial role in efficient electrocatalytic water splitting. Also, the results obtained from density functional theory (DFT + U = 0–8 eV), where U is the on-site Coulomb repulsion parameter also known as Hubbard U, based electronic structure calculations confirm that Zn doping constructively modifies the electronic structure, in both the valence band and the conduction band, and found to be suitable in tailoring the carrier’s effective masses of electrons and holes. The decrease in electron’s effective masses together with large differences between the effective masses of electrons and holes is noticed, which is found to be mainly responsible for achieving the best water-splitting performance from a 9% Zn-doped NiO sample prepared under vacuum.}, author = {Kiran, Gundegowda Kalligowdanadoddi and Singh, Saurabh and Mahato, Neelima and Sreekanth, Thupakula Venkata Madhukar and Dillip, Gowra Raghupathy and Yoo, Kisoo and Kim, Jonghoon}, issn = {2574-0962}, journal = {ACS Applied Energy Materials}, keywords = {Electrical and Electronic Engineering, Materials Chemistry, Electrochemistry, Energy Engineering and Power Technology, Chemical Engineering (miscellaneous)}, number = {1}, pages = {214--229}, publisher = {American Chemical Society}, title = {{Interface engineering modulation combined with electronic structure modification of Zn-doped NiO heterostructure for efficient water-splitting activity}}, doi = {10.1021/acsaem.3c02519}, volume = {7}, year = {2024}, } @article{15114, abstract = {As a key liquid organic hydrogen carrier, investigating the decomposition of formic acid (HCOOH) on the Pd (1 1 1) transition metal surface is imperative for harnessing hydrogen energy. Despite a multitude of studies, the major mechanisms and key intermediates involved in the dehydrogenation process of formic acid remain a great topic of debate due to ambiguous adsorbate interactions. In this research, we develop an advanced microkinetic model based on first-principles calculations, accounting for adsorbate–adsorbate interactions. Our study unveils a comprehensive mechanism for the Pd (1 1 1) surface, highlighting the significance of coverage effects in formic acid dehydrogenation. Our findings unequivocally demonstrate that H coverage on the Pd (1 1 1) surface renders formic acid more susceptible to decompose into H2 and CO2 through COOH intermediates. Consistent with experimental results, the selectivity of H2 in the decomposition of formic acid on the Pd (1 1 1) surface approaches 100 %. Considering the influence of H coverage, our kinetic analysis aligns perfectly with experimental values at a temperature of 373 K.}, author = {Yao, Zihao and Liu, Xu and Bunting, Rhys and Wang, Jianguo}, issn = {0009-2509}, journal = {Chemical Engineering Science}, publisher = {Elsevier}, title = {{Unravelling the reaction mechanism for H2 production via formic acid decomposition over Pd: Coverage-dependent microkinetic modeling}}, doi = {10.1016/j.ces.2024.119959}, volume = {291}, year = {2024}, } @article{15182, abstract = {Thermoelectric materials convert heat into electricity, with a broad range of applications near room temperature (RT). However, the library of RT high-performance materials is limited. Traditional high-temperature synthetic methods constrain the range of materials achievable, hindering the ability to surpass crystal structure limitations and engineer defects. Here, a solution-based synthetic approach is introduced, enabling RT synthesis of powders and exploration of densification at lower temperatures to influence the material's microstructure. The approach is exemplified by Ag2Se, an n-type alternative to bismuth telluride. It is demonstrated that the concentration of Ag interstitials, grain boundaries, and dislocations are directly correlated to the sintering temperature, and achieve a figure of merit of 1.1 from RT to 100 °C after optimization. Moreover, insights into and resolve Ag2Se's challenges are provided, including stoichiometry issues leading to irreproducible performances. This work highlights the potential of RT solution synthesis in expanding the repertoire of high-performance thermoelectric materials for practical applications.}, author = {Kleinhanns, Tobias and Milillo, Francesco and Calcabrini, Mariano and Fiedler, Christine and Horta, Sharona and Balazs, Daniel and Strumolo, Marissa J. and Hasler, Roger and Llorca, Jordi and Tkadletz, Michael and Brutchey, Richard L. and Ibáñez, Maria}, issn = {1614-6840}, journal = {Advanced Energy Materials}, publisher = {Wiley}, title = {{A route to high thermoelectric performance: Solution‐based control of microstructure and composition in Ag2Se}}, doi = {10.1002/aenm.202400408}, year = {2024}, } @article{15166, abstract = {Reducing defects boosts room-temperature performance of a thermoelectric device}, author = {Navita, Navita and Ibáñez, Maria}, issn = {1095-9203}, journal = {Science}, number = {6688}, pages = {1184}, publisher = {American Association for the Advancement of Science}, title = {{Electron highways are cooler}}, doi = {10.1126/science.ado4077}, volume = {383}, year = {2024}, } @article{12832, abstract = {The development of cost-effective, high-activity and stable bifunctional catalysts for the oxygen reduction and evolution reactions (ORR/OER) is essential for zinc–air batteries (ZABs) to reach the market. Such catalysts must contain multiple adsorption/reaction sites to cope with the high demands of reversible oxygen electrodes. Herein, we propose a high entropy alloy (HEA) based on relatively abundant elements as a bifunctional ORR/OER catalyst. More specifically, we detail the synthesis of a CrMnFeCoNi HEA through a low-temperature solution-based approach. Such HEA displays superior OER performance with an overpotential of 265 mV at a current density of 10 mA/cm2, and a 37.9 mV/dec Tafel slope, well above the properties of a standard commercial catalyst based on RuO2. This high performance is partially explained by the presence of twinned defects, the incidence of large lattice distortions, and the electronic synergy between the different components, being Cr key to decreasing the energy barrier of the OER rate-determining step. CrMnFeCoNi also displays superior ORR performance with a half-potential of 0.78 V and an onset potential of 0.88 V, comparable with commercial Pt/C. The potential gap (Egap) between the OER overpotential and the ORR half-potential of CrMnFeCoNi is just 0.734 V. Taking advantage of these outstanding properties, ZABs are assembled using the CrMnFeCoNi HEA as air cathode and a zinc foil as the anode. The assembled cells provide an open-circuit voltage of 1.489 V, i.e. 90% of its theoretical limit (1.66 V), a peak power density of 116.5 mW/cm2, and a specific capacity of 836 mAh/g that stays stable for more than 10 days of continuous cycling, i.e. 720 cycles @ 8 mA/cm2 and 16.6 days of continuous cycling, i.e. 1200 cycles @ 5 mA/cm2.}, author = {He, Ren and Yang, Linlin and Zhang, Yu and Wang, Xiang and Lee, Seungho and Zhang, Ting and Li, Lingxiao and Liang, Zhifu and Chen, Jingwei and Li, Junshan and Ostovari Moghaddam, Ahmad and Llorca, Jordi and Ibáñez, Maria and Arbiol, Jordi and Xu, Ying and Cabot, Andreu}, issn = {2405-8297}, journal = {Energy Storage Materials}, number = {4}, pages = {287--298}, publisher = {Elsevier}, title = {{A CrMnFeCoNi high entropy alloy boosting oxygen evolution/reduction reactions and zinc-air battery performance}}, doi = {10.1016/j.ensm.2023.03.022}, volume = {58}, year = {2023}, }