GuanHua Chen

Multimetallic single-atom catalysts (SACs) have emerged as promising candidates for electrocatalytic reactions. However, identifying bifunctional multimetallic SACs capable of efficiently catalyzing both the oxygen reduction and methanol oxidation reactions (ORR and MOR), applicable to direct methanol fuel cells, remains challenging due to the vast compositional design space. Here, we propose a defective graphene-supported multimetallic SAC (M1M2M3M4M5-SAC) incorporating Mn, Pt, Fe, Ni, Co, and Cu for simultaneous MOR and ORR catalysis. Density functional theory (DFT) calculations along with machine learning (ML) predictions reveal that the Co active site in PtFeNiCoCu-SAC delivers the most favorable performance, exhibiting ORR and MOR overpotentials of 0.47 and 0.46 V, respectively. Guided by these insights, we synthesized PtFeNiCoCu-SAC and a nitrogen-doped sample, confirming their atomic structures using X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and scanning transmission electron microscopy (STEM). Electrochemical measurements validate the theoretical predictions: PtFeNiCoCu-SAC achieves an experimental ORR overpotential of 0.30 VRHE and a Tafel slope of 114 mV/dec at –1 mA/cm2, along with a half-wave potential of 0.86 VRHE. This catalyst also demonstrates good MOR activity, with a pronounced oxidation peak at 0.97 VRHE. Therefore, this work establishes a DFT- and ML-guided strategy for the accelerated rational design of multimetallic SACs and highlights PtFeNiCoCu-SAC as a promising bifunctional catalyst for energy-conversion applications.

Open dumping remains a dominant municipal solid waste disposal practice globally, including in megacities whose populations and economic output rival that of small countries. Sanitary landfilling is a common transition away from open dumping, yet system-level feasibility does not translate into household affordability. Here we quantify this divergence using an integrated city-scale framework that combines spatial landfill siting, engineering-based net-present-value modeling, and satellite-derived metropolitan gross domestic product. Applying this framework across six developing megacities with over 100 million residents, we find that all cities possess surplus land meeting screening-level suitability criteria. Required cost-recovery tipping fees range from 54–130 US dollars per tonne, with 5 ^th –95 ^th -percentile intervals of ±25%–30% under joint parameter uncertainty. Under full household cost recovery, these fees imply annual disposal costs equivalent to 1.2%–2.0% of the minimum wage, whereas associated revenue requirements represent only 0.26%–1.04% of metropolitan gross domestic product. Across cities, household affordability is uncorrelated with metropolitan economic capacity. Landfill depth is the dominant engineering control on affordability, particularly in high-rainfall systems, but cost allocation exerts greater leverage than any design parameter. Thus, technically and macroscopically feasible landfills may remain difficult to sustain through direct household cost recovery without cross-subsidization and public financing.

Stabilizing electrode/electrolyte interphases is crucial for high‐performance lithium–sulfur batteries; however, simultaneously fabricating robust interphases on both the lithium anode and sulfur cathode is challenging. Here, we report an anion‐transferring functional electrolyte containing non‐expendable tetramethylammonium (TMA) bromide that enables the in situ formation of LiF‐rich interphases on both electrodes. The TMA ⁺ cations act as ion carriers that electrostatically shuttle PF ₆ − anions from the bulk electrolyte to the electrode/electrolyte interfaces in the form of ion pairs. This localized enrichment of PF ₆ ⁻ facilitates its electrochemical decomposition, leading to the formation of a uniform LiF‐rich solid electrolyte interphase on the anode and a cathode‐electrolyte interphase on the sulfur cathode. The LiF‐rich interphases show a high Young's modulus, which help suppress interfacial parasitic reactions and Li dendrite formation. The adsorbed TMA ⁺ cations form an electrostatic shielding layer that mitigates local Li ⁺ flux heterogeneity, further suppressing dendrite growth. When applied to Li‐SPAN batteries, they maintain a 92% capacity retention after 350 cycles at 1 C and deliver a high reversible capacity of 1039 mAh g ⁻¹ after 300 cycles at 0.5 C. This work provides an innovative alternative to conventional interphase engineering for stabilizing lithium battery interphases.

Electrocatalytic oxidation of glycerol toward high-value C3 products on Pd-based catalysts presents a promising strategy for upgrading and converting glycerol. However, C3 intermediates often adsorb too tightly on Pd-based catalyst surfaces during glycerol oxidation, leading to C–C bond cleavage. Herein, cubic-shaped PdBi nanoparticles with tunable Ni doping levels are successfully synthesized through a one-step solvothermal method. Owing to the downshift of d-band center originating from the introduction of Bi and Ni as well as the cubic shape, the PdBiNi ternary nanocubes (NCs) exhibit excellent electrocatalytic performance for the glycerol oxidation reaction (GOR). Specifically, Pd83Bi12Ni5 NCs with the lowest d-band center exhibit a specific activity of 61.12 mA cmgeo–2 and a mass activity of 5.34 A mgPd–1. Notably, the Faradaic efficiency (FE) toward C3 products exceeds 97%. In situ Fourier transform infrared spectroscopy and density functional theory calculations show that key C3 intermediates are easily desorbed from the catalyst surface, thereby suppressing C–C bond cleavage and thus preventing overoxidation into low-value products. In addition, Pd83Bi12Ni5 NCs possess long-term durability over the course of 16 cycles (1 h/cycle) with an FE for C3 products between 92.5% and 97.6% upon scale-up deployment in a flow electrolyzer, validating its feasibility in practical operations.

Direct electrosynthesis of hydroxylamine (NH2OH) from nitrate offers a promising alternative for upgrading nitrogenous product in chemical industry. However, catalyst aging, especially in acidic media, remains a critical challenge due to the irreversible surface reconstruction under cathodic potentials, which limits long-term catalytic activity. Here, we develop an eco-efficient regenerative catalyst system that overcomes this durability bottleneck through a dynamic in situ catalyst self-repair strategy. By adding trace Bi3+ in solution, active metallic Bi nanofractals form on demand during electrolysis, delivering a 91.0% Faradaic efficiency for electrochemical HNO3-to-NH2OH conversion. Periodically switching to open-circuit potential fully resets the aged catalyst back into its ionic state without extra energy inputs. Leveraging this reversible Bi3+/Bi redox cycle, we demonstrate a continuous operation of HNO3-to-NH2OH conversion for 30 days, with a consistent product selectivity of over 90% and current density of ~ 0.4 A cm-2. This potential-driven regenerative strategy provides an efficient approach for sustainable synthesis of fine chemicals.

Based on anion intercalation chemistry, dual-ion batteries (DIBs) show advantages including high operating voltages (>5.0 V), intrinsic safety of oxygen-free graphite cathode, metal-free environmental friendliness, and competitive cost. In stark contrast to the well-established diffusion mechanisms for small cations (e.g., Li⁺, Na⁺) in conventional "rocking-chair" batteries, the transport behavior of anions, which act as the pivotal capacity-determining charge carriers in DIBs, remains largely unexplored, particularly regarding how their large ionic radii and distinct solvation dynamics dictate diffusion kinetics. Herein, an ultrafast anion-hopping mechanism is identified, which is intrinsically governed by large ionic radius and high charge delocalization that engender weaker Coulombic interactions with solvent molecules and a consequently loose solvation microenvironment. To thermodynamically favor this low-barrier transport while suppressing parasitic solvent cointercalation, the anion-solvent affinity is further attenuated by engineering an oxidation-resistant localized high-concentration electrolyte (LHCE) paired with a wettable cellulose separator. Through this synergistic strategy, an inorganic-rich cathode-electrolyte interphase (CEI) is constructed to effectively inhibit detrimental solvent cointercalation while facilitating rapid anion desolvation to fully realize the intrinsic high-rate kinetics. As a result, the DIBs based on anion intercalation chemistry retain a reversible capacity of 69.10 mAh g^-1 at an ultrahigh rate of 200C with a long lifespan over 50,000 cycles. The understanding of anion transport behavior and solvation microenvironment offers insights for designing electrolytes toward the development of high-voltage DIBs with fast reaction kinetics and other high-energy batteries.

Dual-ion batteries (DIBs) have emerged as a promising next-generation energy storage technology with compelling advantages induced by anion intercalation mechanism, including high operating voltage (> 4.8 V), abundant raw materials of dual-carbon electrodes, intrinsic electrode safety, and environmental friendliness. However, this mechanism at the cathode side leads to new challenges different from conventional lithium-ion batteries, such as high-voltage electrolyte decomposition, solvent co-intercalation, and limited capacity. In this review, beyond the fundamental understanding and recent progress of DIBs, we systematically discuss their challenges, such as electrolyte decomposition at high voltages, solvent co-intercalation, interfacial instability, asymmetric electrode kinetics, and limited capacity. Corresponding strategies are then summarized, ranging from the design of electrolytes with high oxidation resistance and anion solvation microenvironment regulation to electrode–electrolyte interfacial construction and the discovery of cathode materials with high capacity. The strategies for dynamic matching between cathode and anode, as well as designing more reliable dual-carbon full cells, are further discussed. Finally, prospects for future research are outlined, with emphasis on advanced characterization technologies, theoretical modeling, and rational design of electrode and electrolyte systems. This review provides a roadmap for advancing high-voltage DIBs toward practical applications in large-scale and sustainable energy storage.