Shijie You

Biological wastewater treatment in cold regions faces a low-efficiency and high-energy paradox due to low-temperature inhibition. Inspired by plant phototropism, this study reports bioinspired phototropic endogenous heating (Bio-PEH) based on the underwater opto-thermomechanical response. Upon illumination, cryopolymerized macroporous reduced graphene oxide@poly(N-isopropylacrylamide) fibers undergo asymmetric contraction, which reorients the illuminated surface to be normal to the light vector, so as to maximize photothermal flux under oblique incidence. Meanwhile, flash heating further enhances water-confined heat transfer and expands the effective heating domain. Bio-PEH arrays raise bulk wastewater from 7.8 to 30.2 °C, which improves NH4+ removal by 2.8-fold, accounting for 25.3–169.7% enhancement compared with Joule heating (JH), direct solar heating (DH), and static endogenous heating (SEH). Global simulations further indicate multifold thermal compensation at high latitudes with substantial carbon and energy cost reduction. This study provides a biophysically inspired strategy by utilizing opto-thermomechanical response to realize heating of low-temperature wastewater, making wastewater treatment in cold regions more efficient, economical, and sustainable.

Electrokinetic remediation (EKR) holds promise for in situ cleanup of heavy-metal-contaminated soils, yet rational design has been hampered by the undetectability of process parameters and physical fields. This study reported the inversion of EKR process parameters and electro-hydro-chemical (EHC) fields from limited-view and sparse data by physics-informed neural networks that embed the coupled Richards–Nernst–Planck equations (RNP-PINNs). Reaction-transport stiffness in the RNP equation was mitigated by local-equilibrium formulation, field-wise subnetworks, physics-based nondimensionalization, and sequentially coupled optimization. Pointwise pH values and endpoint total-Pb data were used for inversion of half-adsorption pH (pH50), dimensionless electroosmotic scaling factor (Keos), and H+ buffering coefficient (RH), together with the neural-network parameters. The parameters were tightly clustered across 500 bootstrap refits (Keos = 0.8–0.9, RH = 18.5–19.2, pH50 = 2.9–3.2), revealing weak pairwise compensation (absolute Pearson correlations ≤0.13). This allowed inversion of the spatiotemporal EHC fields with RMSEs of 1.3 × 10–1 mol m–3 d–1 for total-Pb transport and 2 × 10–3 d–1 for Richards equation residuals. The RNP-PINNs offered mechanistic insights into the way saturation reorganized pore-water transport, accelerated acid-front propagation, and promoted Pb redistribution and re-adsorption near the pH front. Compared with conventional theoretical numerical modeling or experimental investigation, this study provides a “theory + data” double-driven paradigm for the inversion of EKR processes.

High‐pressure reverse osmosis concentrates (HPROC) generated from coal chemical zero‐liquid‐discharge processes accumulate nitrate in high‐salinity matrices that deteriorate downstream salt recovery and nitrogen management. This necessitates selective nitrate conversion before evaporation‐crystallization. Electrocatalytic reduction offers a promising route to convert nitrate into ammonia, yet electrocatalyst design remains largely empirical, complicating the development of manufacturable electrodes for practical applications. Herein we developed a literature‐informed interpretable machine learning (ML) framework to screen the CuNi@FeO electrocatalyst toward highly selective nitrate‐to‐ammonia conversion under high‐salinity conditions. The self‐supporting CuNi@FeO was fabricated by spontaneous deposition on sacrificial iron foam and it could realize spatially and energetically nitrate activation, hydrogen supply, and hydrogen evolution reaction (HER) suppression, accounting for a Faradaic efficiency (FE) of 98.74% and an ammonia yield of 19.56 mg h ⁻¹ cm ⁻² at −1.0 V vs. reversible hydrogen electrode (RHE). Operando spectroscopy and theoretical calculations revealed a synergistic multisite pathway involving the sequential *NO ₃ →*N→*NH _x conversion. The membrane‐electrode assembly reactor could sustain 200 mA cm ⁻² for over 100 h and ammonia FE of 91.46% at cell voltage of 2.5 V during treatment of real industrial wastewater concentrate. This work establishes a paradigm shift to ML‐powered screening of electrocatalyst toward scalable nitrate valorization from industrial concentrates.

Recovering ammonium from wastewater is a promising strategy to mitigate nitrogen pollution and close the anthropogenic nitrogen cycle. Electrosorption offers a green recovery route but suffers from low selectivity and capacity in complex aqueous matrices. Herein, we report a phosphate-functionalized WO3 (PWO)-based Faradaic electrosorption (PWO-FES) platform for selective ammonium recovery through reversible hydrogen bonding-coupled intercalation. Phosphate functionalization introduces electron-rich oxygen sites that preferentially form directional N–H···O interactions with NH4+, resulting in stronger affinity than that for competing cations (K+, Na+, Ca2+ and Mg2+) with high selectivity coefficients of 9–25. When integrated into a continuous-flow module, the PWO-FES system recovers 89.9% of ammonium from actual swine wastewater over 8 cycles. The average energy consumption is only 4.7 kWh kg–1 N, with an average current efficiency of 81.1%. Over 100 h of consecutive operation, the system maintains 82.7–90.3% ammonium recovery with high stability. The recovered ammonium-rich sulfate fertilizer supports plant growth and nitrogen uptake in pot experiments at levels comparable to commercial ammonium sulfate. Life cycle assessment indicates the potential for reduced environmental burdens compared with conventional anaerobic-oxic treatment. This work demonstrates a robust, low-energy, and scalable platform for selective ammonium recovery and fertilizer production, advancing sustainable circular nitrogen management.

Electrochemical co‐reduction of CO ₂ and NO ₃ ⁻ is a promising route for sustainable urea synthesis, but its efficiency is limited by kinetic mismatch between CO ₂ RR and NO ₃ RR, and unfavorable adsorption–migration of *CO for C─N coupling. Herein, we design a nickel single‐atom catalyst anchored on ZnO (Ni _SA /ZnO) to coordinate CO ₂ RR and NO ₃ RR kinetics by promoting C─N coupling for efficient urea electrosynthesis. At −0.8 V versus the reversible hydrogen electrode, Ni _SA /ZnO achieves urea yield rate of 41.38 mmol h ⁻¹ g _cat ⁻¹ and Faradaic efficiency of 31.47%. In situ spectroscopic characterizations and density functional theory (DFT) calculations collectively reveal the formation of atomically defined Ni─O─Zn interfacial bridges, inducing charge redistribution and intrinsic electronic gradient across adjacent metal sites. This electronic heterogeneity enables spatially differentiated reaction pathways, with Ni sites favoring for CO ₂ activation toward *CO formation, while neighboring Zn sites facilitate NO ₃ ⁻ reduction to *NH ₂ . Meanwhile, DFT calculations suggest that the interfacial electronic gradient thermodynamically drives *CO migration from Ni to Zn sites, which co‐localizes the key intermediates with a lowered barrier for subsequent C─N coupling. This work demonstrates that atomic‐scale interfacial bridge engineering can overcome kinetic bottlenecks in sustainable urea electrosynthesis, providing a general principle for regulating intermediate spillover and coupling in multistep electrocatalysis.

Ammonium-containing wastewater represents both an environmental burden and a recoverable nitrogen resource. Here we develop an electrochromic self-perception recovery (ECSPR) system that integrates selective intercalation, intrinsic electrochromism and data-driven control for recovering ammonium to produce value-added fertilizer in a smart manner. The system employs a copper hexacyanoferrate (CuHCF) electrode capable of selective NH₄⁺ intercalation (selectivity coefficient of 5–38 versus other cations) with high capacity (2.2–2.7 mmol g⁻¹). Fe-dominated redox conversion with secondary Cu valence modulation couples charge transfer with reversible color switching, enabling visible self-perception of adsorption-desorption states. Image recognition and machine learning convert electrode images into quantitative adsorption states, which are used as the decision variable to schedule adsorption-desorption and route flows in real time. In continuous-flow operation with actual swine wastewater, the ECSPR system achieves cumulative recovery efficiency of 90.2% over 10 cycles with self-feedback regulation at energy consumption of 4.9 kWh kg⁻¹ N on average. Liquid ammonium sulfate fertilizer is produced directly with comparable agronomic performance to commercial products. Life-cycle and techno-economic analyses further indicate environmental benefits and economic feasibility. Overall, this study provides an intelligent strategy for ammonium recovery and fertilizer production from wastewater, making wastewater treatment more economical and more sustainable.

The practical deployment of electrochemical hydrogen peroxide (H₂O₂) production is severely hampered by the corrosive superoxide radicals (O₂^•−) generated at industrial current densities via a one-electron-transfer process, which rapidly degrade active sites and catalysts, consequently deteriorating long-term stability. Inspired by the natural manganese superoxide dismutase (Mn-SOD) enzyme, we designed a biomimetic CoMn-diatomic catalyst (CoMn-DACs), where the Co−N₄ sites primarily drive the two-electron oxygen reduction reaction (2e⁻ ORR) for the selective H₂O₂ production, while the adjacent Mn−N₄ sites function as SOD-mimetic nanozymes, efficiently reversely converting O₂^•− radicals into H₂O₂, thus bypassing the destructive reaction pathway. Combined operando spectroscopy and density functional theory calculations reveal the dual functions of Mn sites in facilitating O₂^•− conversion and optimizing the *OOH adsorption energy on Co centers via the Co−Mn orbital coupling, which induces electronic structure redistribution and moderates the interaction between Co sites and oxygen intermediates toward highly selective and stable H₂O₂ production. Correspondingly, bioinspired CoMn-DACs achieve 99.3% H₂O₂ selectivity with an onset potential of 0.83 V (vs. RHE) and a maximum H₂O₂ production rate of 6.35 mM mg_cat⁻¹, surpassing the state-of-the-art catalyst, while maintaining 83.0−85.1% FE during 200 h continuous operation at 200 mA cm⁻². A techno-economic analysis confirms the practical viability of this system, projecting a low H₂O₂ production cost of US$0.371 kg⁻¹ when operated directly with ambient air, significantly outperforming the conventional anthraquinone process (US$1.50 kg⁻¹). This work achieves durable electrosynthesis by emulating natural radical defense mechanisms, enabling enhanced stability and selectivity in energy-efficient H₂O₂ production.

The electrochemical 2e^– oxygen reduction reaction (ORR) offers a promising pathway for on-site hydrogen peroxide (H₂O₂) production as an alternative to the anthraquinone process. However, challenges remain for low selectivity and a trade-off between selectivity and activity (TOSA). This study develops a novel thermodynamic regulation strategy to improve the selectivity toward 2e^– ORR by suppressing competitive 4e^– ORR. With the decoupled decisive factors, the selectivity and activity of 2e^– ORR can be independently tuned to boost H₂O₂ production aiming to break the TOSA. Based on density functional theory predictions and experimental validations, a vanadium single atom electrocatalyst with an axially coordinated −NO₂ ligand exhibits 98.06% selectivity toward 2e^– ORR while the activity approaches the theoretical limit. The H₂O₂ yield rate reaches up to 7.47 mol g_cat^–1 h^–1 in a neutral electrolyte at 0.30 V vs RHE in a flow cell. Moreover, on-site production and in situ utilization of H₂O₂ for degrading typical recalcitrant organic pollutants are demonstrated in a dual-cathode electron–Fenton system. Tetracycline and phenol (20 mg L^–1) can be degraded with an efficiency up to 100% in 120 min. This study provides a proof-of-concept demonstration of a thermodynamic regulation strategy to promote H₂O₂ production by addressing low selectivity and TOSA of 2e^– ORR, and on-site production and in situ utilization of H₂O₂ have broader implications in environmental scenarios.